Added OpenGL debug callback support and context changes.

1. We no longer hardcode a 3.2 profile. It chooses the latest profile that fits out description.
2. I added three tables and macros to help with the offsets compared to the variables to help reading. Read comments for more info.
3. I added glewExperimental being set. What a dumb "feature". It doesn't help anything...
Remove enable statements. This should be done in platform-independent code using GLEW.
Added gl_update (does nothing for now).

Fix previous commit..
Added GLX version check and assures context is set to none on failure.

Fixed the location glewExperimental was being set to just before glewInit() (where it should be).
Minor style fixup
Change _DEBUG coverage a bit
I removed GL-specific extension checking to a platform independent file.
I also fixed autoconf to find wxWidgets 2.9 without user intervention
Removed unused code and added more organization
Merge pull request #21 from computerquip/master

Various Changes to OpenGL intialization