Better handle the dirty state of Airmap's flightplan

Adjust fly overlay height
Change minimum Qt version to 5.11+

Restore QGC to its normal UI layout (buttons on toolbar)

Stable merge

Stable merge

Offline Maps: Allow custom build override of min/max zoom levels, max tile download

Fixed Wing Landing Pattern: Use standard Altitude Mode labeling

Fix: Tile errors were reported twice

Consistent Altitutude Mode labelling in all complex items

Use consistent Altitude Mode labeling

Use new extraUnitField

Show extra unit in small font

Reduce space between graphic and text

Use standard Altitude Mode labeling

Add new file

Fix double tile download error reporting

Prevent double reporting of tile download errors

Offline Maps: Allow custom build settings overrides

Object ownership handled by SettingsGroup base class

ArduRover: Add Follow mode