velocity hold: fix axes swap, tune gains down
attitude control: ui sensitivity is now parameterized

and the control loops themselves are just specified by setpoint
and units for setpoints are always radians
gcs: debug is a separate stream
position UI has tunable sensitivity
add Flight.Control.StateDerivativePID, same as StatePID with user provided deriv est
ivory-px4-hw: GPS reports time in Position
hil: add time to Position
Navigation.Velocity: estimate Position acceleration per fresh sample