Remove unused code

- 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

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

Support for reusable InstrumentValueArea control

Refactor instrument value controls

Allow split of current segment

New MapLineArrow control

Also rename QmlPageInfo to QmlComponentInfo to cover more use cases

Used to display items associated with Flight Plan on Map

Replacing some icons, cleaning up help text, etc.

- Delete all old map code

- Restructured a number of MissionItem properties as well

- Moved all MavManager functionality to Vehicle
- Updated all code to use Vehicle instead of MavManager
- Removed MavManager