minor symfony#8747 Update components/* articles to Symfony 4 (javiereguiluz)

This PR was squashed before being merged into the 4.0 branch (closes symfony#8747).

Discussion
----------

Update components/* articles to Symfony 4

Commits
-------

4af878f Define a deprecated page as orphan to avoid RST issues
37c4c06 Deprecate the LockHandler utility
5828b2f Remove a deleted article
0c0c076 Remove app/ references
8b48cc9 Remove bundle references
a4db8b8 Use .yaml instead of .yml as extension
a8bc89c Removed the deprecated Console Dialog Helper
c34b0bf Removed the deprecated class_loader component

Author: weaverryan

_build/redirection_map

@@ -295,10 +295,18 @@
 /components/browser_kit/introduction /components/browser_kit
 /components/class_loader/introduction /components/class_loader
 /components/class_loader/index /components/class_loader
+/components/class_loader/cache_class_loader /components/class_loader
+/components/class_loader/class_loader /components/class_loader
+/components/class_loader/class_map_generator /components/class_loader
+/components/class_loader/debug_class_loader /components/class_loader
+/components/class_loader/map_class_loader /components/class_loader
+/components/class_loader/map_class_loader /components/class_loader
+/components/class_loader/psr4_class_loader /components/class_loader
 /components/config/introduction /components/config
 /components/config/index /components/config
 /components/console/helpers/tablehelper /components/console/helpers/table
 /components/console/helpers/progresshelper /components/console/helpers/progressbar
+/components/console/helpers/dialoghelper /components/console/helpers/questionhelper
 /components/console/introduction /components/console
 /components/console/index /components/console
 /components/debug/class_loader /components/debug

components/class_loader.rst

@@ -4,72 +4,9 @@
 The ClassLoader Component
 =========================
 
-    The ClassLoader component provides tools to autoload your classes and
-    cache their locations for performance.
-
 .. caution::
 
-    The ClassLoader component was deprecated in Symfony 3.3 and it will be
-    removed in 4.0. As an alternative, use any of the `class loading optimizations`_
-    provided by Composer.
-
-Usage
------
-
-Whenever you reference a class that has not been required or included yet,
-PHP uses the `autoloading mechanism`_ to delegate the loading of a file
-defining the class. Symfony provides three autoloaders, which are able to
-load your classes:
-
-* :doc:`/components/class_loader/class_loader`: loads classes that follow
-  the `PSR-0`_ class naming standard;
-
-* :doc:`/components/class_loader/psr4_class_loader`: loads classes that follow
-  the `PSR-4`_ class naming standard;
-
-* :doc:`/components/class_loader/map_class_loader`: loads classes using
-  a static map from class name to file path.
-
-Additionally, the Symfony ClassLoader component ships with a wrapper class
-which makes it possible
-:doc:`to cache the results of a class loader </components/class_loader/cache_class_loader>`.
-
-When using the :doc:`Debug component </components/debug>`, you
-can also use a special :ref:`DebugClassLoader <component-debug-class-loader>`
-that eases debugging by throwing more helpful exceptions when a class could
-not be found by a class loader.
-
-Installation
-------------
-
-You can install the component in 2 different ways:
-
-* :doc:`Install it via Composer </components/using_components>` (``symfony/class-loader``
-  on `Packagist`_);
-* Use the official Git repository (https://github.com/symfony/class-loader).
-
-.. include:: /components/require_autoload.rst.inc
-
-Learn More
-----------
-
-.. toctree::
-    :glob:
-    :maxdepth: 1
-
-    class_loader/class_loader
-    class_loader/class_map_generator.rst
-    class_loader/debug_class_loader.rst
-    class_loader/map_class_loader.rst
-    class_loader/psr4_class_loader.rst
-
-.. toctree::
-    :hidden:
-
-    class_loader/cache_class_loader
+    The ClassLoader component was removed in Symfony 4.0. As an alternative, use
+    any of the `class loading optimizations`_ provided by Composer.
 
-.. _PSR-0: http://www.php-fig.org/psr/psr-0/
-.. _PSR-4: http://www.php-fig.org/psr/psr-4/
-.. _`autoloading mechanism`: http://php.net/manual/en/language.oop5.autoload.php
-.. _Packagist: https://packagist.org/packages/symfony/class-loader
 .. _`class loading optimizations`: https://getcomposer.org/doc/articles/autoloader-optimization.md