This allows the desired speed limiting (by acceleration) to be done before the speed-to-throttle PID controller is run.
This is required so the avoidance calls (which work on the desired speed) can be run after limiting but before the PID controllers
This limits the change in desired turn rate to reduce impossible requests which should help avoid overshoot
Also add rotation rate limit to turn-rate controller
Throttle controller has these advantages over existing controller:
based on velocity in vehicle's forward-back axis rather than ground-speed
straight-forward PID controller using speed error as input
speed control acceleration limts
stop control slows vehicle smoothly
configurable filtering
Steer controller has these advantages over existing controller:
output scaled properly for skid-steering vehicles
layered P and PID controller for angular error and rate control
configurable filtering
