Sprite Class

A sprite is an interactive element of a game.
A Sprite is not directly related with graphic feature, it is a logical element of the game.
A Sprite has various attributes and behavior as collisionArea to define its active region.
It is able to execute something on every game tick to define its transformation (for example changing frame to be displayed by a TiledGraphicObject).
Sprites are registered in the game engine, and the engine ensures that every Sprite will evolve in time calling its execute method.
A usual implementation of an element of a game is to define it as son of something printable (a GraphicObject) and to implements Sprite interface to be registered in the game engine and evolving with it.
New: now getCollisionArea() returns a CollisionArea object and not a Rectangle.