OpenGL2: Support half floats for texcoords and vertex colors.
Remove accidentally added increment.
Clear window buffer when it's created

When starting the game in windowed mode, the window buffer used whatever
was on the screen before running the game. Kind of like you could see
through the window, but it doesn't update what happens behind it.

It makes it look like something is broken or non-responsive.

So clear the window opengl buffer to black.

Credit to theinvsblman for the code.
OpenGL2: remove lightmap support from generic glsl shader.
This path was barely used and doing this compiles fewer shaders.
OpenGL2: Add support for parallax occlusion mapping.
OpenGL2: Bit more parallax optimization.
Correct a few OpenGL variable types

Affectly no change for desktop OpenGL.
Use correct types for OpenGLES support.
Remove unfinished OpenGL display list code

It seems unlikely anyone is going to do anything with this aside from stub
it out in OpenGLES ports.
Don't set fog image border color

GL1's R_CreateImage sets GL texture to 0 before it ends, so border color is not
applied to the fog image. GL_CLAMP is not used for fog image (in either renderer),
so it would presumably not be used even if applied to the fog image.
Fix stencil shadows not drawing if has 500 or more vertexes

Stencil shadow is not drawn if a mesh, or multiple meshes with the same
entity and shader, have more than 500 vertexes. The issue is caused by storing
the projected positions in the tess vertex buffer. Use a new array instead.
OpenGL2: Ensure tess VAO is bound before using it.
OpenGL2: Fix face culling.
Fix saving/loading glyph 255 in RegisterFont

The glyph for character 255 (lower case y with two dots above it) was
rendered, but it's glyph information was not stored in fontInfo_t and
not saved into .dat file (including the ones in Team Arena).

Attempting to load it from existing .dat font files is fine because
shader name is "" and gets 0 handle. The handle was already 0 anyway.
Fix negative glyph index in Team Arena text functions

Team Arena's text functions cast signed char values to int and use as an array index.
This works fine for values 0 to 127, but not for -128 to -1 which are a negative array index.
Instead use "character & 255" like client and original Q3 ui/cgame string drawing code.
Merge branch 'master' into game/darks