Added occlusion culling capability in the BGE.
More info: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.49/Game_Engine#BGE_Scenegraph_improvement
MSVC, scons, cmake, Makefile updated.
Other minor performance improvements:
- The rasterizer was computing the openGL model matrix of the objects too many times
- DBVT view frustrum culling was not properly culling behind the near plane:
Large objects behind the camera were sent to the GPU
- Remove all references to mesh split/join feature as it is not yet functional
In a simple test with ~12000 verts, overall BGE startup time went from ~4.5 sec to a bit under a second.
- before adding each vert it did a check for a duplicates.
- Using RAS_Polygon verts can give a lot of duplicates because the verts also store UV's and normals.
- Was increasing the array one item at a time, now resize the array once.
- Use the blender mesh mvert array rather then RAS_TexVert's, so needed to include some DNA headers.
