Removed giant block of commented code
Added support for retina displays

Makes liberal use of SDL_GL_GetDrawableSize to find out what the actual size of the window is.
Compensates for scaled mouse coordinates.
Had to switch to SDL_WINDOW_FULLSCREEN_DESKTOP to get things to work, unsure why.
Added support for retina DPI detection
CapabilitiesGetScreenDPI now returns an actual DPI (PPI to be specific) value as opposed to the earlier strange measurement
Uses the actual window size (instead of the requested size) to calculate the scale ratio
Hooked into notification for changed window scaling, this will probably cause a crash on earlier versions of OS X
Triggers a resize event when the window PPI changes
Removed stray fprintfs
Added check to make sure the computer supports the windowDidChangeBackingProperties notification (10.7 and lower does not and causes a crash)