also direct throttle nudge replaced with speed nudge
calc_speed_max estimates vehicle's top speed based on cruise-speed and
cruise-throttle
steering mode now provides total target speed instead of using speed plug
throttle nudge
motor limits provided to attitude control to stop i-term buildup
uses negative desired speed instead of reversed flag
reporting to GCS uses new throttle controller
braking is simply enabled and allows a reverse motor output regardless of vehicle
speed