Wiimote support

[Hamcha]

Currently the only supported method of controlling the hovercraft is via the gamecube controller, even on Wii.

We should support using the Wiimote on the Wii version since that's the main controller there. There are some challenges coming from the original hovercraft:

• There are 3 different types of "Wiimote control": Wiimote, Wiimote + Nunchuck and Motion Plus (We'll ignore Nunchuck+Motion plus since it doesn't have anything useful over standard Mote+Nunchuck)
• The standard wiimote does not have a 3-axis gyroscope, instead relying on acceleration and tracking. When put sideways tracking is impossible, and the accelerometers are pretty much useless at detecting yaw (at least with libogc). This makes using the Wiimote as a wheel a problem.
• I never tried the Wii wheel, I don't know how Mario Kart works but it looks kinda weird that they can get away with the sideways wiimote, I should get one and see if the plastic shell holds any interesting secret.

I don't expect Wiimote+Nunchuck and Motion plus to give me issues, as they both solve the orientation problem in different ways (Nunchuck has an analog stick and Motion plus has a proper gyroscope).