OpenGL profiling

[Orphis]

Restore is used when the state has been altered externally, thus no way to know what may have changed. It was kind of required when I implemented it, now, don't know if that's still the case.
If there are redundant calls, then you could break on them in gDebugger and see where they come from. Or grep through the code to search who is calling glViewport and not going through our state tracker.