- removed several race conditions. What happens is that in many activity
	  and even in GCompris core, we set callback before the end of the initialisation
	  like displaying all the content. It is then possible for the user to click
	  start an action while it's not completly displayed. It ends up either in graphical
	  inconsistencies or may even crash.
	  Hopefully, this may solve some intermitent crashes we have in GCompris.
	- Fixed several compilation issues
	- No more warnings when sqlite is disabled