Bring master up to date with Stable 3.4

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.

ArduPilot: ChibiOS flash support for Pixhawk family boards

Fix trad heli mappings

Fixes

Formatting changes

Fix NuttX build url format

iOS build and mobile sizing

Fix xcode project and restore LaunchImage
Cleanup unused icons

ArduPilot ChibiOS support

* '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

Upstream stable merge

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