Added a Create Box option to generate a 100^3 box
Added an icon for the box generator

|SOURCE|
[XNA/Editor]
* Added a static property for the GraphicsDevice to use when adding a new box
  to the list of boxes
[XNA/Cube]
* A cube is rendered with a given colour (this is actually handled by the view
  instead of from the cube itself), and minimum and maximum extents determine
  the size of the cube
[PerspectiveViewControl]
* The Cubes List property from the Editor form is used to render created cubes
[OrthogonalViewControl]
* The Cubes List property from the Editor form is used to render created cubes
[GraphicsDeviceService]
* When a GraphicsDevice is created, the Editor form's GraphicsDevice property
  is set to the newly created GraphicsDevice