Soft mouse

da-nah-nah! nah-nah! soft-mouse! [/batman]

Anyway, a while ago I was chatting with @robn about needing a UI drawn soft mouse so that I could progress with my Oculus Rift integration and he put this together. It has kind of languished in limob since then existing only on his branch and my LibOVR branch until today when I decided it needed a mouse cursor and should move into mainline.

I've added 3 mouse cursors, the only way to select between them is by changing the code right now... patches welcome. I picked the black one as the default because I'm a goddamn Goth :)

Andy