BGE UI: removing "use_occlusion_culling" from the ui
(and marking rna as deprecated)

I talked with Benoit Bolsee and Mitchell Stokes and they both agreed that
the feature should be removed.

In case someone was actually using it the rna is still available. But next
release we remove both the rna, the DNA and the flag in the code.

I did a simple benchmark with tons of cubes, and the DBVT culling (use_occlusion_culling=True)
always perform better than when it's off. Even when no occluder objects are in the scene.


git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54126 954f8c5b-7b00-dc11-b283-0030488c597c