Some drivers dont support const array
Add a function to query supported glsl ver
Do not build shadow shader without gs support.
Merge commit 'f3e2da881a4d394c4ca902548e788f5b4c0bdd81'

* commit 'f3e2da881a4d394c4ca902548e788f5b4c0bdd81':
  Do not build shadow shader without gs support.
  Add a function to query supported glsl ver
  Some drivers dont support const array
Definitively fix stencil bug thx to graphitemaster from irc
SkyShader: attrib position is not always 0.
Add file path when a compiler error arise.
Fix a  shader compile failure on nvidia.
Factorise cubevbo/vao in shader.cpp
Do not render billboard outside of transparent pass
GPUParticles: some factorisation
Add an overload for draw2DImage with a single color
Use new single-color overload in font where possible
Add missing icon
Add depth of field to the color_level shader. As vincent requested. Something cleaner need to be done
clamp overload was ambiguous.
Don't use glDebugMessageCallbackARB if null
Fixed compiler warnings.