High framerates work with multithreading

I moved the calcs to a background queue, then executed UI changes on main thread.

I had to use an array to pass the pitch/roll parameters, as per this answer: http://stackoverflow.com/questions/1460589/how-do-i-call-performselectoronmainthread-with-an-selector-that-takes-1-argum

I've tested this at 200 fps on iphone5 and is silky smooth