Fixed a couple of bugs in the motor code for the position/velocity motor control. I switched it so that if it reaches the motor target it resets position to 0 instead of trying to control the velocity directly. Let the position control of the motor handle it.
Also fixed a bug in the new adapter code were some values were not getting reset.
1. Hooked up the code to add part interface pointers to the BodyPart. Forgot to do that before.
2. Added a new pointer to the motor control unit for a part. There can only be one motor control unit per body part.
3. Added quantization of the speed and velocity for a motor system. Real servos have a fixed point precision for speed and velocity. So this makes the simulation reproduce that behavior.