[Sprite] sourceRectangle is public now.
[Level] Added two methods called when a level is enabled and disabled from the LevelManager
[LevelManager] Give the possibility to load a level without initialization.
[Math] Various fixes + new methods.
[Rectangle/Vector] Don't use +value|0 on float values.
Font: Fixed measureText to use the correct size. Added clone() method to SpriteFont.
Other: Some fixes
Fixes for touch and mouse input