New VehicleLinkManager implementation

Co-authored-by: Anton Erasmus <antonerasm@gmail.com>

Clean up references to MainRootWindow globals

PX4 multi-battery setup

Support unlimited compasses, plus all sort of other ui fixup

Fix logging

Add separate Gyro cal support

Move calibration methods to Vehicle

Unified photo/video control which works with mavlink cameras and just video stream

Switch to Controls 2 version of QGCButton

Shorten meta data keys for smaller file sizes

Fix max channel handling

New QGCFileDownload support for bit.ly style redirects and file name

Add support for compass priority

LinkInterface and Vehicle uses mutexes to synchronize writing bytes to the link instead of queued signals

More warnings cleanup
Android fix
More
More
More
Fix typo
Update android compiler warnings
Fix android compiler warnings
More android compiler warnings

Add support for Json file string translations

App messages now use simple modal message dialogs. Vehicle messages continue to use non-modal popup.

Remove unused HIL code

Fix Radio button problems

Fix RadioButton group problems. Rework RTL settings to match correct usage.

Fix RadioButton group problems

Flight mode fix, cherry picked from master

Remove ArduPilot Follow Me support from Stable

timer.start() and timer.stop() were breaking the 'running' binding of
the timer

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

Change follow to work above home altitude only