Terrain fixes

Fix swapped climb/descent

Fix incorrect qCWarning

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

Compass Cal: Don't show compass orientations for fixed orientation vehicles.

Plan: Fix defaulting when you "Change Command"

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

Don't show compass orientations for fixed orientation vehicles.

Fix Change Command parameter default setting

Windows: Install new version does not delete AppData from previous install.

Install new version does not delete AppData from previous install.

Fixes

* 'Stable_V3.4' of https://github.com/mavlink/qgroundcontrol:
  Change Command only supported for Simple Items
  Prompt for Reboot after compass cal
  Respect app units

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

Plan: Change Command only supported for Simple Items

Prompt for Reboot after compass cal

Change Command only supported for Simple Items

Prompt for Reboot after compass cal

Polygon Circle: Respect app units

Fix xcode project and restore LaunchImage
Cleanup unused icons

Respect app units

Terrain: Use NaN for bad elevation value

Use NaN to signal lower level error

More terrain query fixes/logging

Kick off terrain query after load

Don't query intermediate state

Better logging

Add new Help page under Settings

Terrain Tiles: Persist header info as doubles

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

Terrain: Better error handing

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

Fix failure handling

Use qCWarning for internal errors

Wrap text in Offline Map Options