Auto-complete friendly function prototypes
Is it possible to mimic same behavior like `glcorearb.h` with `GL_GLEXT_PROTOTYPES` defined? Current implementation hides function prototypes and makes auto-complete feature of IDEs almost useless.

![out](https://cloud.githubusercontent.com/assets/1075690/4023310/dea8f5b4-2b85-11e4-8681-4b0a424c4650.png)

Thanks!
