It is not convenient having to change a parameter to change a gimbal
from RC input to mavlink input mode or back. This refactor changes the
behaviour to use whatever is available, RC or mavlink commands.
Once a mavlink command is followed, control can be taken back using RC,
however, this requires a clear stick change.
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.