LComponent: fixed possible bug: leak+callback not found: don't change
name once set, just updated the name on JUCE side
LJUCEApplication: fixed: moreThanOneInstanceAllowed callback result not retrieved
LComponent/LuaO: fixed: as segfault'ing with Component
lua/init: set LDEBUG ASAP
Main: return exit status
LJUCEApplication: added get/setApplicationReturnValue
Main: set default value to 0 for rc
LJUCEApplication: initialised pushes the initialised DocumentWindow to callback
- refactored: ApplicationCommandManager has moved from LDocumentWindow to
LJUCEApplication, in order to be able to handle multiple DocumentWindows

- LPopupMenu is impacted by this refactoring in addCommandItem

- for the same reason, added a new method to LDocumentWindow:
  closeWindow, maybe temporarilly if something equivalent were to be
  found in JUCE

- attached to closeWindow is LJUCEApplication::deleteWindow,
  LJUCEApplication now storing references of LDocumentWindow
  in an Array of ScopedPointers

- in LJUCEApplication, refactored initialise as general method
  to be used by all possible initialisation callbacks, depending
  on OS

- in LJUCEApplication, added a Luce specific (static) method getInstance