[GL Overlays] Initial Commit (w/ double buffer & AA disabled)

Committing what I have figured out, may abandon this idea.  I run into a
bizarre performance issue with double buffering on.  FRAPS reports 60FPS
but it is definitely not.   CPU is also 2x higher than without double
buffering.
Merge remote-tracking branch 'origin/dev/2.0' into feature/gl-overlays
[GL Overlays] Further refactoring

Original functionality restored, including working AA along with double
buffering.  Required disabling the automatic management of buffer
swapping.
[GL Overlays] Fix glitchy screen during init & first resize
[GL Overlays] Actually fix glitchy screen on init

Still didn't work on release builds, which appear to fill the buffer
with random GPU data on init