Blender Git Loki

- found the bad line in Ghost that preventing closing windows.
I've mailed Maarten to verify it, this commit is for test at other
OSX platforms.

- this was the baddie:
setDrawingContextType(GHOST_kDrawingContextTypeNone);
it was called in the window destructor, for each window closed.
I've hacked in a temporal global var to store the mainwindow. When this
line is only called for mainwindow, it all works smoothly.

- next commit is needed too!