Click on button depend on the shape in addition to its rectangle

- 2 new ShapeTypes (Rectangle, Arbirtrary) --> the latter one uses the new algorithm
- Arbitrary currently doesn't work for WP8 and W8 due to a bug in the Texture2D.GetData method in MonoGame (working for WindowsGL though) (how about Android?) --> just remove the Shape property on the Play and U-button to behave it normally