[MP] Rend2: Use correct dlight image.
[MP] Rend2: Remove altivec unused q3 stuff.
[MP] Rend2: Use r_ext_compress_textures instead of r_ext_compressed_textures for the actual cvar name to match vanilla renderer.
[MP] Rend2: Merged some stuff from ioq3 rend2 that helps with r_floatLightmap being off.
OpenGL2: Set RGBM to use a multiplier of 1, and only use it with HDR lightmaps.
OpenGL2: Fix bug in ColorToRGBM().
OpenGL2: Oops, set lightmap alpha to 1.