Added GHOST_TUns16 numOfAASamples parameter to GHOST_CreateWindow to specify the number of AA samples (null if no AA wanted)
Implemented it in the cascade of GHOST classes.
Full implementation currently done for OSX/Cocoa, stubs for other OSes.
Moguri : it's ready for your win32 implementation !
Note that fallback to a non AA window (if gfx card doesn't support AA) is done inside GHOST OS specific layer, so that blender windowmanager still gets its window created properly.