GBitmap Changes:
Added all other formats to gbitmap that we support
gbitmap now supports cubemaps
added converters for all these other formats
added stb_image_resize for extrudemips so we can extrude mipmaps for all other formats
GFXTextureManager
Can now directly make cubemaps and texture arrays based on the GFXTextureProfile
API implementations for all functions that cubemaps and arrays needed
The fix adds a sanity check to the D3D and GL device enumeration function that exits early if there's no registered display from the OS(implying it's running in commandline).
With newer versions of SDL, attempting to enumerate the GL device causes a segfault because the OS will return back a valid context, but the context isn't actually valid. So when tested against, it crashes. Avoiding enumerating the device when you're not in a position to render works around the issue.
TODO: If the machine is running in terminal-only mode, and thus has no valid render context, but still has a monitor plugged into the machine, it can sidestep the sanity check and still result in a segfault. Need a more robust check for that circumstance in a future fix.
* Explicitly request a GL 3.2 context
* Enable 'experimental' extensions on glew (This appears necessary to get glew to work with explictly set GL versions)
