uncomment drawing of plateau's borders
add ControleurJeux to MainWindow

    it manages creation of plateaux
    change constructor of Plateau to have the lvl passed in param
    add some forgotten delete in MainWindow
add changing level when one is done (2 lvl atm)

    lvl files are stored in static array of ControleurJeux
    add prochainNiveau() to go to the next level or tell MainWindow we
    are done
    put static fields initialization in a method
    move timer to Plateau, stop it when objectifs are done
    add lvl/2.txt