Add a 3D mode to path_endpoint. This allows FlyDirect waypoints to do
vertical movements without changing position.
Improved automatic landing algorithm to better track descend speed.
Desired descend speed is now a FlightModeSetting.
Adds a 3D mode to path_vector. This allows vertical path segments without
position changes. PathStatus now also contains correction_direction and
path_direction to make path following behaviour more transparent.
We don't want zero-length path_direction vector.
Revert to the original behaviour of calling "fly_endpoint" if we have a
zero-length path.
Don't limit the path to strictly be between start and endpoint.
Missing argument for path_endpoint added.
Merge remote-tracking branch 'origin/D-Lite/PathFollowerImprovements' into corvuscorax/OP-1156_pathfollower-unification
OP-1156 refactored pathfollower - new unified module as delayed callback - compiles but untested