Show the link indicator in the tool bar if two or more links are connected and at least one of them is a high latency link.
Show in the link indicator if a link is inactive.

This setting enables/disables the LinkIndicator toolbar in which the primary link can be chosen.

Automated preflight checklist: Initial commit. Note that this requires an autopilot firmware that writes the respective health flags in the SYS_STATUS mavlink message

This reverts commit 52160d80.

Just use settings defaults

Instead of hardcoded "QGroundContorl" strings

No more user prompting

Convert bool settings to SettingsFact

* Holds all the settings for the app
* Allows core plugin to override default values

- Shot Interval in Survey
- Much change to time/distance calc