Adds MNT_DO_STAB for whether to stabilize by default.
Adds MNT_RANGE_{PITCH,ROLL,YAW} for the output range of each output channel in AUX mode (instead of hardcoded 360 degrees).
Adds MNT_OFF_{PITCH,ROLL,YAW} for adjusting the zero point of each output channel.
This will initialize those structs with zero in all fields not set
and all fields set will only be change once to the final value not
wasting CPU time zeroing it.
This will guarantee that no non-unitialized structs will have
a trash value on from_external causing it to be sent to the
MAVLink channel without need it.
This splits vmount into inputs and outputs modules with a small API in
between. It allows for greater flexibility, as any input method can be
combined with any output method. At the same time it is easy to add a new
input or output module.
Matthew Edwards