Correct error, create by the next commit.
Add access, of Sprite.
Add move on mount stairs animation.
Code clean up.
No atomic commit sorry :

* Game system, isn't artemis system.
* IngameInputSystem test if need return at LevelMenu.
add menu_video.png
add default_menu.png
set default menu background
When ned mount on stairs wait the end of animation to return one level selector.
Merge origin/master
fix #34 Intro uniquement au premier lancement et menu pour la revoir.
Correct segfault, when ned mount stairs.
Ned mount stairs.
global scale
optim entity system
simplify drawsystem
remove uneed import
Fixe #85, ok is ugly.
When ned wait boost maki up hands and down hands.
Closed #65.