New VehicleLinkManager implementation

function "QLineF::IntersectionType QLineF::intersects(const QLineF &line, QPointF *intersectionPoint) const" was introduced in Qt 5.14, and QLineF::intersect is obsolete.

see also:
https://doc.qt.io/qt-5.14/qlinef-obsolete.html
https://doc.qt.io/qt-5.14/qlinef.html#intersects

Refactor/fixes for ProximityRadar and friends

QGCFileDialog remove separate mobile fileExtension properties

Clean up references to MainRootWindow globals

Fix bugs related to dynamic fact groups

Full BATTERY_STATUS support

PX4 multi-battery setup

Remove unused code

Remove logging

- add NOTIFY for distanceSensor property
- add DistanceSensorReadingsChange() callback prototype

- revert excessive NOTIFY
- adding MaxSensor into DistanceSensor frame handling

- add proximity radar view in map view
- add proximity radar view in video view

change distance label positioning in video view

clean up unwanted comments

- space up proximity sectors
- revert unwanted changes in qgroundcontrol.qrc

squashed commits

Less twitchy value grid width sizing

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

Switch to Controls 2 version of QGCButton

Remove unused code

Telemetry Values bar at center bottom

More flight mode, vtol mode, armed into main status

Ready To Fly support based on MAV_SYS_STATUS_PREARM_CHECK

Shorten meta data keys for smaller file sizes

Replace qFuzzyCompare with better functioning QGC::fuzzyCompare

Support stacked component dialogs

Horizontal scrolling as needed

Support for Vehicle and Firmware classes