Saving waypoint using Lua script

[Eosbandi (Andras Schaffer)]

It is for copter but easily can changed for rover as well…

Special features request for agricultural drones

In the meantime, I worked up a Lua script that inserts a waypoint at the location where a battery failsafe occurs and stores its waypoint index in a file on the SD card. If the waypoint index stored in that file is non-zero at boot time, the mission will resume at the inserted waypoint. I tested in SITL with a fair amount of success but implore you to do the same before implementing this on a large agricultural vehicle. There is an underlying assumption that the path from the takeoff location t…