GLDEBUGPROC incorrectly defined

Issue #57 resolved
fergothegreat
created an issue

The last parameter of GLDEBUGPROC should not be const.

http://www.opengl.org/sdk/docs/man/xhtml/glDebugMessageCallback.xml

Edit: Never mind, it turns out the mistake is with SDK docs on opengl.org. It is const after all.

http://www.opengl.org/registry/specs/KHR/debug.txt