1. Receiver.c for ground allows disabled channels for all but yaw and throttle
2. Reciever.c applies a deadband on throttle 0 position
3. Arming understands ground have a 0 throttle position
4. Actuator optimisations in general and fixes for mixing
5. Actuator mixer support for reversible motors
This module includes all the receiver IO and parsing/failsafe
functionality of ManualControl, but does none of the interpretations in
regards to flight mode / actuator control or arming that was included in
the old ManualControl
In a second step the old ManualControl module needs to be adapted to do
only these ommitted things in a modular way - as a delayed callback
