- previously we only kept track of starting flying while in auto which gets reset when switching in and out of auto and on takeoff/land. Now we keep track of a "global" one that will track the is_flying flag regardless of the flight mode.
fixes https://github.com/diydrones/ardupilot/issues/2778
When executing a takeoff, and the throttle is suppressed, but we're already flying, we should unsuppress the throttle. We can get into this situation if we reset the mission in-flight.
- enabled via new param LAND_ABORT_THR default is 0 (disabled)
- Triggered via 95% throttle during landing, a landing abort will take place.
- This copies all takeoff params for right now, we can make this better later if needed
- added mission item command to NAV_LAND which is the abort takeoff altitude. If 0 then use last takeoff if available, else use 30m
- hold heading, just like takeoff, until altitude is reached
- pitch is constrained to takeoff pitch, or else 10deg if not available
- After abort altitude is reached, the normal landing restart happens (DO_LAND_START or decrement mission)
- restart landing by jumping to DO_LAND_START or decrement mission on mode change