Support creating GL 3.2 contexts on MacOSX.
Replace dynamic casts with static on glws.
We know as a fact that the type matches.
Update glws Cocoa bindings too.
Cleanup X11 event handling.
Fixes an infinite loop on GlxDrawable::show() in certain traces.
Add a few comments/links to Cocoa development resources.
Use Cocoa on Mac OS X.
It will enable better control for OpenGL context creation.