Expose root plan keys

Also cleaning up annoying c++14 warnings.

Fix swapped climb/descent

Fix incorrect qCWarning

Hack fix for terrain crash when new query comes through before old query is complete

Fix Change Command parameter default setting

Fix trad heli mappings

Formatting changes

Fix NuttX build url format

ArduPilot ChibiOS support

Hide flight speed and camera section for ArduPilot. This is because it doesn't allow mission items to be before the TAKEOFF command.

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

Change Command only supported for Simple Items

Prompt for Reboot after compass cal

Respect app units

Use NaN to signal lower level error

Kick off terrain query after load

Don't query intermediate state

Better logging

Add new Help page under Settings

Persist tile info as doubles. This prevent float/double precision match errors at the edge of tiles.

Bump terrain tile version due to format change

Turn internal errors (elevation == -1) into failed query to prevent bogus elevation from reaching upper layers.