Fix handling of dirty bit when home position changes from vehicle side

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

Fix planned home position set when takeoff has no coordinate in it

Fix terrain NaN making it all the way to Planned Home altitude.

Fix resume mission item count bug

Fix Change Command parameter default setting

Don't add takeoff as first item when it doesn't make sense for vehicle

Add flight plan deletion

Moved flight planning away from "Flight Management" to its own class. Planning does not need a connected vehicle.