Added (UI) support for vehicles exposing more than one camera.

Adding missing qgcView to QGCMapPolygonVisuals instance in SurveyMapVisual.qml

Eliminated flight widget "states"
Define flight widget top margin (plugin options)

Added a signal handler to force toggle the switch. Not sure why the normal signal is not being respected.

Moved "Grid Lines" out of General Options and into the Video Stream Widget
Made a QGC custom Switch element

Clarify the title of the "Video Stream" panel (instead of just "Video")

Also added Vehicle.flightTime to default setup

Update the user model to a single controller instead of multiple