Pull request n°3

Content
Package each exercise of welcome into its own repertory
Package each exercise of recursion into its own repertory
Update po4a.conf ( to be okay with the two packaging )
Update French translation
Move the world of turmite ( TurmiteWorld.java & TurmiteWorldView.java ) from lessons.welcome.cell to jlm.universe.turmite 
Correct the identation of some file
Correct some typo