Use persistent buffer mapping for dynamic buffer objects.
Merge branch 'master' into vertexpack
Remove USE_DEFORM_VERTEXES macro.
Remove USE_EYE_OUTSIDE macro.
Merge branch 'master' into vertexpack

Conflicts:
	src/engine/renderer/tr_vbo.cpp
Add cvar to disable GL_ARB_sync.
Fix building on old GLEW.
Fix inverted if condition.

This caused the engine to allocate a too small VBO and thus resulted
in low FPS or even crashed the game.
Remove USE_FRUSTUM_CULLING macro.
Remove BRIGHTPASS_FILTER macro.
Remove USE_GBUFFER macro.
Refactor vertex deformation code.
Merge branch 'master' into vertexpack
Merge all available bounding boxes for IQM culling.

Needed if the bounding boxes in the .iqm file are too small. Some
iqm exporters seem to have problems there.
Merge branch 'vertexpack'