Started work on adding a bounding sphere

|SOURCE|
[Common/BoundingSphere]
* The BoundingSphere is intended to be used as a non-renderable and renderable
  (if desired) built-in primitive
[Common/Renderer]
* Added a BeginLightPass member function to allow for rendering deferred lights
* VERTEX_POSITION is used as a vertex type which just contains the position
* The appropriate GL state is set in the GBufferBegin and GBufferEnd calls