Fix null pointer dereference
Merge branch 'master' of github.com:Unvanquished/Unvanquished
Change RE_SetColorGrading to use the renderer command list

It is not efficient to make OpenGL calls from the main thread with smp enabled
Use R_SyncRenderThread in more places
Reduce the number of calls to GLimp_SetCurrentContext()

GLimp_FrontEndSleep only needs to block until the renderer thread is finished, it does not need to acquire the OpenGL context.
Fix crash with SMP enabled
CMakeList: add USE_SMP back to be able to test it
GLimp: call XInitThreads before creating a GL device
Fix smp exception
Call R_SyncRenderThread in RE_StoreImage
Remove the GLSL optimiser with extreme prejudice.

(Let the OpenGL lib do the optimising for us.)
Remove GLSL optimiser code from the GL3 renderer.
Allow SMP without destroying the window on each map load
Fix SMP for vanilla renderer
RendererGL: Add a basic FXAA implementation
mesa/FXAA: GLSL preprocessor names containing ‘__’ are reserved.
Define FXAA_GLSL_120 or FXAA_GLSL_130 as needed.
Check the shader language version rather than the driver ‘type’.
FXAA: better detect the GLSL version
Fix glsl version 1.20 detection

The string returned by glGetString( GL_SHADING_LANGUAGE_VERSION ) may have the format "major_number.minor_number.release_number" or have vendor specific information added to the end;