LayeredCanvas Class

This is a concrete implementation of a GameCanvas.
Its idea is to offer a 5 layers Canvas to implement z-Order for printing GraphicObjects.
This class implements a layer manager in which you can add and remove graphic objects specifying also the level in which they will be shown.
Then manages the order for printing objects.
Remember: this class ensure the correct order for printing layer, but inside the layer you have not any control on order of printing. So if you want to ensure that object A will be print over object B they have to belong to different layers.
PS: remember to remove object when you don’t need them anymore anyhow then will not be garbaged!!!