FSWheelModule does not work properly with 1.1.x

[Ruedii]

FSWheelModule seems to exhibit several issues in 1.1.x

1. Wheels "jitter" sometimes leading to explosions.
2. Wheel motors simply run constantly, not properly responding to rover controls.
3. Steering does not provide proper traction, leading to the vehicle drifting and spinning out uncontrolably.

It is likely the wheel module codebase needs an entire rewrite, or at least a new shim for the newly updated Unity/PhysX wheel modules. After this update, the wheels will likely need to be greatly retuned and rebalanced.