OpenGL2: Reduce glsl shader count by using a uniform to disable textures.
OpenGL2: Revisit fragment tangent space calculation, and remove tangent space lighting.
OpenGL2: Some small shader optimizations.
OpenGL2: Reimplement soft overbright to avoid a framebuffer blit.
OpenGL2: Prefer VBO/IBO sizes of around 4MB.
Fix running if built on OS X 10.9

strncpy with in == out causes signal 6 if built on OS X 10.9.
(If built on older OS X versions, the game works on 10.9 though.)

It was happening in COM_StripExtension during map load.
Merge remote-tracking branch 'ioquake3/master'
Update Spearmint GL2 for recent upstream changes