* AMDs new driver fixed many issues in the OpenGL driver. No reason to
keep these hacks. In addition the upgrade to 4.3 guarantees the
existance of required extensions, so no need to check for them
* renderer_opengl: Namespace OpenGL code
Namespaces all OpenGL code under the OpenGL namespace.
Prevents polluting the global namespace and allows clear distinction
between other renderers' code in the future.
* Also namespace TextureCubeConfig
This was very likely intended to be a logical OR based off the
conditioning and testing of inversion in one case.
Even if this was intentional, this is the kind of non-obvious thing one
should be clarifying with a comment.