documentation update using markdownlint

Author: ddmitov

CREDITS.md

@@ -1,5 +1,5 @@
-Perl Executing Browser - Thanks and Credits
---------------------------------------------------------------------------------
+# Perl Executing Browser - Thanks and Credits
+
 Amata mea Argeia - gratiam magnam tibi ago!  
 Patientia tua in studiis meis computatoriis auxilium meum maximum!  
 
@@ -33,6 +33,7 @@ Thanks to Daniel Muey and all contributors of the File::Copy::Recursive CPAN mod
 https://metacpan.org/pod/File::Copy::Recursive  
 
 ## Qt
+
 https://github.com/richmoore/qt-examples/tree/master/sitespecificbrowser  
 https://github.com/OtterBrowser/otter-browser/blob/master/src/modules/backends/web/qtwebengine/QtWebEnginePage.cpp  
 https://github.com/OtterBrowser/otter-browser/blob/master/src/modules/backends/web/qtwebengine/QtWebEnginePage.h  
@@ -150,6 +151,7 @@ https://unix.stackexchange.com/questions/116254/how-do-i-change-which-version-of
 https://www.developpez.net/forums/d1549582/c-cpp/bibliotheques/qt/moteurs-web/runjavascript-fonction-lambda-plante/  
 
 ## Perl 5
+
 https://perlbrew.pl/  
 https://github.com/skaji/relocatable-perl  
 http://strawberryperl.com/  
@@ -181,6 +183,7 @@ https://perlmaven.com/recursive-subroutines
 http://lauraliparulo.altervista.org/first-steps-in-sqlite-and-perl/  
 
 ## HTML, CSS & JavaScript
+
 https://www.w3schools.com/js/js_loop_for.asp  
 https://www.w3schools.com/jsref/prop_html_innerhtml.asp  
 https://www.w3schools.com/jsref/met_form_submit.asp  
@@ -205,6 +208,10 @@ https://jquery.com/
 http://youmightnotneedjquery.com/  
 
 ## Markdown
+
+https://github.com/DavidAnson/markdownlint  
+https://dlaa.me/markdownlint/  
+
 https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet  
 https://github.com/IQAndreas/markdown-licenses  
 
@@ -214,6 +221,7 @@ https://stackoverflow.com/questions/23989232/is-there-a-way-to-represent-a-direc
 https://meta.stackexchange.com/questions/70356/key-stroke-combination-markdown  
 
 ## Bash
+
 http://tldp.org/LDP/abs/html/fto.html  
 http://tldp.org/LDP/abs/html/functions.html  
 
@@ -233,20 +241,25 @@ https://www.cyberciti.biz/faq/unix-linux-bsd-appleosx-bash-assign-variable-comma
 https://www.tutorialspoint.com/unix/unix-regular-expressions.htm  
 https://ryanstutorials.net/bash-scripting-tutorial/bash-functions.php  
 
-## Mac
+## AppImage
+
+https://www.freedesktop.org/software/appstream/docs/chap-Quickstart.html  
+https://specifications.freedesktop.org/desktop-entry-spec/1.1/apa.html  
+
+## Macintosh
+
 http://leonid.shevtsov.me/en/how-to-create-icns-icons-for-os-x  
 https://iconverticons.com/online/  
 
 ## Google Chrome Unsafe Ports
+
 https://superuser.com/questions/188058/which-ports-are-considered-unsafe-on-chrome  
 
 ## GitHub
+
 https://github.com/github/linguist#overrides  
 
 ## Travis CI
+
 https://docs.travis-ci.com/user/reference/xenial/  
 https://stackoverflow.com/questions/25737062/travis-ci-for-a-qt5-project  
-
-## AppImage
-https://www.freedesktop.org/software/appstream/docs/chap-Quickstart.html  
-https://specifications.freedesktop.org/desktop-entry-spec/1.1/apa.html  

README.md

@@ -1,5 +1,4 @@
-Perl Executing Browser
---------------------------------------------------------------------------------
+# Perl Executing Browser
 
 [![GitHub Version](https://img.shields.io/github/release/ddmitov/perl-executing-browser.svg)](https://github.com/ddmitov/perl-executing-browser/releases)
 [![GitHub License](http://img.shields.io/badge/License-LGPL%20v3-blue.svg)](./LICENSE.md)
@@ -11,6 +10,7 @@ Perl Executing Browser (PEB) is an HTML5 user interface for [Perl 5](https://www
 ![PEB Screenshot](https://github.com/ddmitov/perl-executing-browser/raw/master/doc/screenshot.png "PEB Screenshot")  
 
 ## Contents
+
 * [Quick Start](#quick-start)
 * [Design Objectives](#design-objectives)
 * [Features](#features)
@@ -46,6 +46,7 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
 in the documentation of this project are to be interpreted as described in [RFC 2119](https://www.ietf.org/rfc/rfc2119.txt).  
 
 ## Quick Start
+
 * Common Steps:
   * **1.** Download PEB.
   * **2.** Select your Perl distribution.
@@ -68,13 +69,15 @@ in the documentation of this project are to be interpreted as described in [RFC
   * **5.** Write an appropriate HTML interface and connect it to your server application by traditional web  communication protocols.
 
 ## Design Objectives
+
 * **1. Easy and beautiful graphical user interface for Perl 5 desktop applications**  
 * **2. Fast, zero-installation software**  
 * **3. Cross-platform availability**  
 * **4. Secure solution, serverless by default**  
 * **5. Maximal reuse of existing web technologies and standards**
 
 ## Features
+
 * PEB can be started from any folder without installation procedure.
 * [Perl script output is seamlessly inserted in any local page.](./doc/SETTINGS.md#perl-scripts-api)
 * [Perl scripts with STDIN event loops can be repeatedly fed with data (Linux and Macintosh builds only).](./doc/SETTINGS.md#interactive-perl-scripts)
@@ -87,6 +90,7 @@ in the documentation of this project are to be interpreted as described in [RFC
 * [Optional warning for unsaved data in HTML forms](./doc/SETTINGS.md#html-page-api)
 
 ## Security
+
 * PEB does not need administrative privileges, but will not refuse to use them if needed.
 * PEB does not need and does not implement any server, but will start one if so configured.  
 * Local Perl 5 scripts are executed with no sandbox and they have direct access to local files.
@@ -96,21 +100,25 @@ in the documentation of this project are to be interpreted as described in [RFC
 * Files or folders can not be selected with their full paths from web pages.
 
 ## What PEB Is Not
+
 * PEB is not a general-purpose web browser and does not have all traditional features of general-purpose web browsers.
 * PEB does not embed any Perl interpreter in itself and depends on an external, supposedly relocatable, Perl distribution.
 
 ## Limitations
+
 * Only single-page applications are supported with no pop-up windows and no Perl scripting inside frames.
 * No files can be downloaded.
 * ``QtWebEngine`` builds do not support printing and ``window.print()`` is not supported.
 * Windows builds of PEB do no support [interactive Perl Scripts](./doc/SETTINGS.md#interactive-perl-scripts).
 
 ## History
+
 PEB was started in 2013 by Dimitar D. Mitov as a simple GUI for personal database applications.
 
 ## [Thanks and Credits](CREDITS.md)
 
 ## [License](./LICENSE.md)
+
 This program is free software;  
 you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License,  
 as published by the Free Software Foundation;  
@@ -119,5 +127,6 @@ This program is distributed in the hope that it will be useful, but WITHOUT ANY
 without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 
 ## Authors
+
 Dimitar D. Mitov, 2013 - 2018  
 Valcho Nedelchev, 2014 - 2016  

doc/CONSTANTS.md

@@ -1,5 +1,4 @@
-Perl Executing Browser - Constants
---------------------------------------------------------------------------------
+# Perl Executing Browser - Constants
 
 ## Files and Folders
 
@@ -80,12 +79,14 @@ A typical ``{PEB_executable_directory}`` looks like this:
     If this file is not found, the default icon embedded in the resources of the browser binary is used.
 
 ## Functional Pseudo Filenames
-* **About PEB dialog:** ``about-browser.function``
 
+* **About PEB dialog:** ``about-browser.function``
 * **About Qt dialog:** ``about-qt.function``
 
 ## Specific Keyboard Shortcuts
+
 All specific keyboard shortcuts are available only in the QtWebKit builds of PEB.
+
 * <kbd>Ctrl</kbd> + <kbd>I</kbd> - start QWebInspector
 * <kbd>Ctrl</kbd> + <kbd>P</kbd> - get printer selection dialog. If no printer is configured, no dialog is displayed.
 * <kbd>Ctrl</kbd> + <kbd>R</kbd> - get print preview

doc/LOGGING.md

@@ -1,13 +1,14 @@
-Perl Executing Browser - Logging
---------------------------------------------------------------------------------
+# Perl Executing Browser - Logging
 
 PEB supports unified logging of Perl and JavaScript errors in the JavaScript console.  
 All you need to read error logs is to open the JavaScript console.  
 
 ## Opening the JavaScript Console on QtWebkit Builds
+
 Start the QWebInspector using the keyboard shortcut <kbd>Ctrl</kbd> + <kbd>I</kbd> and go to the ``Console`` tab.  
 
 ## Opening the JavaScript Console on QtWebEngine Builds
+
 Start PEB with the following command-line argument supplying an arbitrary private port:
 
 ```bash

doc/PACKAGING.md

@@ -1,14 +1,15 @@
-Perl Executing Browser - Packaging
---------------------------------------------------------------------------------
+# Perl Executing Browser - Packaging
 
 ## Minimal Relocatable Perl Distribution for PEB
+
 Minimizing the size of a relocatable (or portable) Perl distribution used by a PEB-based application is vital for reducing the size of its distribution package. [Perl Distribution Compactor](https://github.com/ddmitov/perl-executing-browser/blob/master/sdk/compactor.pl) is one solution for this problem. It finds all dependencies of all Perl scripts run by PEB and copies them in a new ``{PEB_executable_directory}/resources/app/perl/lib`` folder. Any unnecessary modules are left behind and the original ``bin`` and ``lib`` folders are saved as ``bin-original`` and ``lib-original``.  
 
 Perl Distribution Compactor must be started from the ``{PEB_executable_directory}/sdk/lib`` folder using [compactor.sh](https://github.com/ddmitov/perl-executing-browser/blob/master/sdk/compactor.sh) on a Linux machine or [compactor.cmd](https://github.com/ddmitov/perl-executing-browser/blob/master/sdk/compactor.cmd) on a Windows machine to make sure that only a relocatable Perl distribution is used.  
 
 Perl Distribution Compactor depends on [Module::ScanDeps](https://metacpan.org/pod/Module::ScanDeps) and [File::Copy::Recursive](https://metacpan.org/pod/File::Copy::Recursive) CPAN modules, which are included in the ``{PEB_executable_directory}/sdk/lib`` directory.
 
 ## AppImage Support
+
 PEB or any PEB-based application can be easily packed as a 64-bit single-file Linux [AppImage](https://appimage.org/) executable by the [AppImage Maker](https://github.com/ddmitov/perl-executing-browser/blob/master/sdk/appimage-maker.sh) script, which has two modes of operation:  
 
 * packing a Perl application together with a PEB executable, its Qt libraries and a relocatable Perl distribution:  

doc/REQUIREMENTS.md

@@ -1,7 +1,7 @@
-Perl Executing Browser - Requirements
---------------------------------------------------------------------------------
+# Perl Executing Browser - Requirements
 
 ## Compile-Time Requirements
+
 The only Linux and Macintosh compile-time requirement of PEB is a Qt development bundle version 5.2 or any later version.  
 
 Compiling Windows binaries of PEB is subject to the following restrictions:  
@@ -13,6 +13,7 @@ Compiling Windows binaries of PEB is subject to the following restrictions:
 * Windows builds of PEB do no support [interactive Perl Scripts](SETTINGS.md#interactive-perl-scripts) with STDIN event loops.
 
 Compiled and tested successfully using:
+
 * [Qt 5.2.0](http://download.qt.io/archive/qt/5.2/5.2.0/) on 32-bit Debian 7 and 32-bit Windows XP
 * [Qt 5.2.1](http://download.qt.io/archive/qt/5.2/5.2.1/) on 64-bit Ubuntu 14.04 and 64-bit OS X 10.9.1, i5
 * [Qt 5.3.0](http://download.qt.io/archive/qt/5.3/5.3.0/) on 64-bit Lubuntu 14.10
@@ -31,6 +32,7 @@ make
 Please note that PEB builds using the ``QtWebKit`` web engine are single-process applications consuming less memory than PEB builds using the ``QtWebEngine`` which are multiprocess applications.  
 
 ## Compile-Time Settings
+
 All compile-time settings require editing the ``src/peb.pro`` project file according to the following instructions.  
 
 * Updated QtWebKit  
@@ -69,6 +71,7 @@ All compile-time settings require editing the ``src/peb.pro`` project file accor
   To make automatically a bundled binary (peb.app) use the [dmg-maker.sh](sdk/dmg-maker.sh) script by Valcho Nedelchev.
 
 ## Runtime Requirements
+
 * Qt 5 libraries.  
 
   The ``ldd`` Linux command can show all dependencies of a PEB executable.  

doc/SETTINGS.md

@@ -1,7 +1,7 @@
-Perl Executing Browser - Settings
---------------------------------------------------------------------------------
+# Perl Executing Browser - Settings
 
 ## Application Filename
+
 The executable binary file of the browser, ``peb``, ``peb.app``, ``peb.dmg`` or ``peb.exe`` by default, can be renamed with no restrictions or additional adjustments. It can take the name of the PEB-based application it is going to run. If log files are wanted, they will take the name of the executable file without the filename extension, whatever the name may be.
 
 ## HTML Page API
@@ -57,6 +57,7 @@ The ``pebSettings`` JavaScript object may have the following properties:
   ``String`` displayed in a JavaScript Confirm popup box when the close button is pressed, but unsaved data in local HTML forms is detected. If no ``closeConfirmation`` object property is found, PEB exits immediately.
 
 ## Perl Scripts API
+
 Every Perl script run by PEB has a JavaScript settings object with an arbitrary name and fixed object properties. The name of the JavaScript settings object with a ``.script`` extension forms settings pseudo filename used to start the Perl script.  
 
 There are three methods to start a local Perl script:  
@@ -132,6 +133,7 @@ A JavaScript settings object for a Perl script run by PEB has the following prop
   ```
 
 ## Interactive Perl Scripts
+
 Each PEB interactive Perl script must have its own event loop waiting constantly for new data on STDIN for a bidirectional connection with PEB. Many interactive scripts can be started simultaneously in one browser window. One script may be started in many instances, provided that it has a JavaScript settings object with an unique name.  
 
 Please note that interactive Perl scripts are not supported by the Windows builds of PEB.  
@@ -200,6 +202,7 @@ The [index.htm](https://github.com/ddmitov/perl-executing-browser/blob/master/re
 The [interactive.pl](https://github.com/ddmitov/perl-executing-browser/blob/master/resources/app/perl/interactive.pl) script of the demo package is an example of a Perl interactive script for PEB.
 
 ## Starting Local Server
+
 A [Mojolicious](http://mojolicious.org/) application or other local Perl server can be started by PEB provided that  
 a ``{PEB_app_directory}/local-server.json`` file is found instead of ``{PEB_app_directory}/index.html``  
 with the following structure:
@@ -234,17 +237,15 @@ with the following structure:
   Privileged ports below or equal to port 1024 are not allowed.  
   The following Google Chrome unsafe ports used by various services are also not allowed:  
 
-  ```
-  2049 - nfs
-  3659 - apple-sasl / PasswordServer
-  4045 - lockd
-  6000 - X11
-  6665 - Alternate IRC [Apple addition]
-  6666 - Alternate IRC [Apple addition]
-  6667 - Standard IRC [Apple addition]
-  6668 - Alternate IRC [Apple addition]
-  6669 - Alternate IRC [Apple addition]
-  ```
+  2049 - nfs  
+  3659 - apple-sasl / PasswordServer  
+  4045 - lockd  
+  6000 - X11  
+  6665 - Alternate IRC [Apple addition]  
+  6666 - Alternate IRC [Apple addition]  
+  6667 - Standard IRC [Apple addition]  
+  6668 - Alternate IRC [Apple addition]  
+  6669 - Alternate IRC [Apple addition]  
 
 * **command-line-arguments**  
 ``Array`` holding all command-line arguments that have to be passed to a local Perl server  
@@ -255,6 +256,7 @@ The ``#PORT#`` keyword within the command-line arguments is substituted with the
 ``shutdown_command`` is not needed if the local server uses a WebSocket connection to detect when PEB is disconnected and shut down on its own - see the [Tabula](https://github.com/ddmitov/tabula) application for an example.
 
 ## Selecting Files and Folders
+
 Selecting files or folders with their full paths is performed by clicking a link to a pseudo filename composed of the name of a JavaScript settings object for the wanted dialog and a ``.dialog`` extension.  
 
 A JavaScript settings object for a filesystem dialog has only two object properties: