[MP] Fix #450 - R_FogFactor segfault

When fixing the render command list, the shader indexes are reassigned
in the sort keys. However, when rebuilding the sort key, the entity num
was not re-shifted into the correct place in the bitfield.
[SP] Update the drawsurf sort code from MP.
Switched MAX_ENTITIES to MAX_REFENTITIES and similar defines.
MAX_SHADERS must remain 13 bits because of the weird sorting stuff with RF_ALPHA_FADE.
[SP] Disable FixRenderCommandList for now.
Merge remote-tracking branch 'upstream/master' into custom