[Toolkit.Input] Change behavior of position returned by MouseManager, now in the range [0,1] in order to avoid windows size dependent position.
[Toolkit.Input] Fix minor potential issue in MouseManager
[Toolkit.Input] Change behavior of PointerManager to return position independent window size in the range [0,1]
[Toolkit.Samples] Change ModelRendering on WP8 to use DrawingSurface instead of DrawingBackgroundSurface
[Toolkit.Game] Add support for custom Width/Height for DrawingSurface.
[Toolkit.Input] Add IEquatable and ==, != operator to KeyboardState, MouseState, PointerPoint
[Toolkit.Graphics] Add RasterizerStateCollection.WireFrame and RasterizerStateCollection.WireFrameCullNone