Added licence boilerplate.
+ Redesigned classes to use (finally!) a more QT and object-oriented pattern :
  LaunchButton handles directly everything about buttons (instead of accessing the GroupButton widget), except context menu.
+ FIXED statistics were mixed up between buttons after sort
+ Improved button sort (most launched first, alphebetical when there is a draw)
Merge branch 'master' of https://github.com/mbellier/launcher

Conflicts:
	README.md