More flexible shader name matching

[c42f]

The case of variable names can cause a mismatch between variables in the file and variables in the shader. This is a bit of an unnecessary pain, and it would be useful if we were a bit more flexible about how the matching worked. For robustness and flexibility the name matching could be a two stage process:

1. Match names exactly if possible, including perfect case matching etc
2. If no match is found, attempt to match by normalizing to all lowercase, (possibly also removing underscores, etc?)

[devshgraphicsprogramming]

I would advise to abandon matching shader inputs to variable names with C++

This has been made obsolete with the layout qualifier https://www.khronos.org/opengl/wiki/Layout_Qualifier_(GLSL)

Since you've migrated to OpenGL 3.3 you can forego the use of most name-based-interface-matching