Fix headers
Start moving towards state independence

-Added state-tracking for matrix mode to glState.c
-Made most matrix op calls explicitly refer to which matrix
-Added early support for Direct State Access when applicable
Changes

-Move all calls to glStencilOp to glStencilOpSeparate so that I can
state track this later
-Rework the stencil operations in the Particle Overdraw code to make
better
Robustness improvements and cleanup
Add framebuffer checking to GL_SetDefaultState
Fixes for VR startup

-Will not trash HUD FOV if VR device is connected/launched after start
-Fix for view weapons clipping if VR mode starts with Q2 start