Finished Wii portion of InputManager and JoystickTest

Finished implementing multiple Wii controller support in the Input
Manager. Added getAxis emulation with smoothing, and cleaned stuff up
in general. Now all Wii Controllers are initialised, and instead just
have a .pluggedIn property that determines whether or not they're
plugged in.

Also refactored JoystickTest to be cleaner, accepts multiple
controllers now. Shows display of virtual joystick.