QML fixes

Adding missing qgcView to QGCMapPolygonVisuals instance in SurveyMapVisual.qml

Joystick axes can now be monitored even when joystick control is disabled

Add highLatency property to LinkConfiguration

Fix bugs in updating priority link

Camera Control

Support remainder of HIGH_LATENCY2 fields

* Also handles correct prioritization of high latency links

Corridor Scan: applyNewAltitude support

UDP Change

Plus various bug fixes from flight testing

Corridor Scan: Support for images in turnaround

Implemented workaround for bug with qml property binding. Now the state of the checkbox will always match up with the state of the outputEnabled.

Joystick axes and buttons can now be monitored even when the
joystick input is disabled.

Fix multiple selected state for offline maps buttons.

More work on better unit tests

And fixes they found

Complex item unit test work

Clickable deadzone

Maintain a list of address/port pairs instead of a address/port map.

Minor improvement to detection of stick recentering after calibration. Without this if you performed a calibration with deadband enabled but one of the deadbands at the end of the calibration was ~0 it would be very difficult to position the stick so that Qgroundcontrol considered the axis to be centered.