Merge branch 'master' of https://github.com/ilag11111/SRB2

With whitespace fixup
OpenGL wall Y offset

Fixed wall textures breaking when Y offset of the wall was too high.
Merge https://github.com/STJr/SRB2
MD2 Texture load fix

Fixes MD2's using sprites on the first frame when they're loaded.
OpenGL Splitscreen Fix

First screen in split-screen is now not completely black.
OpenGL Screen Fading Fix

Screen Wipes now work as they did in 2.0.x.
OpenGL Translucent Midtexture Fix

Translucent Midtextures using holes with textures in them now work when
there is no FOF's above their sector.
Player Spin Frame MD2 Interpolation

Player spin frames on MD2's interpolate correctly when moving slowly.
Compile Win32 EXE with -gdwarf-2
Merge https://github.com/STJr/SRB2
OpenGL Screen Flip

Screen flipping in OpenGL is no longer done by inverting the screen
polygons.
Merge branch 'master' of https://github.com/Sryder13/SRB2
restore ISO C90 support in r_opengl