front: Added some programmatically-set user preferences to UserPrefs.
cleanup: Renamed variable (no functional changes).
front: Nyko PlayPad controller mostly supported.

Still difficult to map the left analog nub, since it sends both
AXIS_X and AXIS_HAT_X (and Y) at the same time.  But all other axes and
buttons are easily mapped now.

This should fix issues with other composite controllers, such as the
OUYA controller, which combine mouse emulation and joysticks on one
device.