Licence recap clarification

Fix arduino#2703

Author: cmaglie

LICENSE

@@ -0,0 +1,22 @@
+
+This file summarize licensing information for parts of Arduino. Anyway,
+this is just a recap and doesn't replace the licensing for each part
+of Arduino, please **always check directly the source code for the
+correct and updated license information**.
+
+- The Arduino IDE is a Java app that is contained in the folders `app`
+and `arduino-core`. This app is a fork of Processing and is released
+under the GPL-2.0 license.
+
+- The Arduino Core for AVR microcontrollers is an embedded-C framework,
+the source code is in the `hardware/arduino/avr` folder and is released
+under the LGPL-2.1 license unless otherwise specified.
+
+- The Arduino Libraries are embedded-C libraries to be used in
+microcontrollers, the source code is in the `libraries` folder they are
+released under various license: LGPL-2.1, Apache-2.0, BSD-3-clause, MIT2
+Please refer to the source code of each library for the correct license.
+
+- The Arduino Examples, contained in the `build/shared/examples` folder
+are released in the public-domain.
+

license.txt renamed to app/LICENSE

@@ -1,15 +1,3 @@
-this file includes licensing information for parts of arduino.
-
-first, the gnu general public license, which covers the main body 
-of the processing/arduino code (in general, all the stuff inside the 'app'
-and 'core' subfolders).
-
-next, the gnu lesser general public license that covers the arduino core
-and libraries.
-
-
-.....................................................................
-
 
                     GNU GENERAL PUBLIC LICENSE
                        Version 2, June 1991