Fix a cmake conflict
Mac OS X: Finally correctly compile on OS X

- Mac now uses redefined qgl* to gl* functions
- Mac uses SDL instead of its own implementation
- Removed some random _fcreator and _ftype externs which were totally random?
- Removed an undefined function call
- Use SIOCGIFADDR instead of OSIOCGIFADDR
- Added a new file in macosx/ called macosx.m which conatins the 2 functions we need
- CMake fixes for the new files