Yet More Stuff

Refactors soundMaster to not break when it is not initialized.
Adds some nice accessors to sliders, makes them based off of a
normalized rect instead of screen coordinates, and factories to create
already sliding sliders.
Adds Cardinal directions
Adds some more functions into ColorF
Adds some WIP matrix stuff into GUIF
Changes GUISkin font switching to hotswap fonts, rather than derive new
GUIStyles.
Adds a few more functions into RectF
Reworks StringF.TimeFormat to have an overload for number of places
Adds GUISliderMessage behaviour, to easily show a message to the user
that they must dismiss to continue.