Add option for using OpenGL legacy.
Merge remote-tracking branch 'origin/master' into opengl-legacy
Switch over to using "my" GL binding repo.
Return error when using unsupported OpenGL funcs.
Add GL version return to Start function.
Add missing documentation.
Fix compiling error.
Update README regarding OpenGL versions.
Eliminate reliance on GLSL layout extension.
Update examples.
Mention Optimus in README.
Mention known Intel HD 4000 issue.
Update README.
Merge pull request #2 from velovix/opengl-legacy

OpenGL Legacy Support Development Is Finished