AP_Scripting: quadplane terrain avoidance with can't make that climb

[timtuxworth]

This is a Lua script that runs continually while a quadplane is in AUTO mode (typically running a mission) and monitors LIDAR readings for dangerously close terrain. If the terrain gets too close, the script will take over the quadplane performing one of three avoidance maneouvers:

1. "Pitching" the plane will pitch up at the maximum rate/speed possible (subject to TECS limits)
2. "Quading" the plane will switch to QHOVER mode and use the VTOL motors to gain altitude as quickly as possible
3. "Can't make that Climb" - the plane will circle left or right up to a safe altitude above approaching terrain.

This has been extensively tested in the wilds of northern Canada.

[timtuxworth]

Hi @IamPete1 and @peterbarker - I wonder if you could take a look at this. It's mostly a Lua script with some added bindings.
Is there anyone else who could/should review it?