Mavlink terrain protocol support

Minimum transect spacing of 0.5 meters

New Create Plan support

Pattern Preset support

Rework complex distance, camera shot count calc for better back compat

Should not rebuild transects when loading. Mission items are already stored in file

Fix mission item generation

Add camera start to transect entry even when taking images throughout survey area.

Fixed camera shot count when trigger distance == 0

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Only adjust existing waypoints. Does not add waypoints.

Plus various bug fixes from flight testing

And fixes they found