Added lightgrid texture based lighting in q3bsp maps by uploading it as a 3D texture...

Added lightgrid texture based lighting in q3bsp maps by uploading it as a 3D texture, to make more accurate and continuous model lighting throughout a scene.  Can be disabled via the mod_q3bsp_lightgrid_texture cvar.

The lightgrid texture based lighting can also be enabled on world surfaces if one desires (mod_q3bsp_lightgrid_world_surfaces cvar) which gives levels a dream-like quality that is globally consistent, can also be enabled for bsp models that are not the world (mod_q3bsp_lightgrid_bsp_surfaces cvar) which may be more useful for ammo pickup models that are bsp or similar.

This frobs the shader glsl crc so expect to update any modified combined*.glsl files as per usual with updates to the embedded shader code.

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@12584 d7cf8633-e32d-0410-b094-e92efae38249