OS X Fullscreen options

This adds some finer control over how fullscreen works on OS X.  Also and importantly, it switches the default fullscreen mode to be the native 10.7 animate-to-new-space way, while the kiosk style method is available through options.

Some remaining rough points to think about are:

* how does this effect secondary display blanking on windows. It's been moved to go-time options
* how to handle full screen at startup - is the animate method appropriate, or should we instead choose kiosk, or should there be options?