GLFramebuffer: Re-enable builtin frame-buffer after initialization.
GLFramebuffer: Adding Constructor and init-option to use as a proxy for the builtin frame-buffer.
GLFramebuffer: Adding isBuiltin method for testing for a native builtin frame-buffer.
GLFramebuffer: Adding parameters for buffer wrap repeat and clamp.
GLFramebuffer: Changing parameter for buffer wrap mode to support any mode.
Now using frame-buffered render pipeline and adding stereoscopic rendering support for HMD with fish-eye lenses. Changing projection/merge shader would enable different output device projections including red-blue/red-green color separation.