Have different modes for the Airspace Widget (Plan/Fly)

Permit refactoring
QGCButton tweaks

Make all argument to AirMap queries based on what the screen shows (bounding rectangle and/or radius), respecting the limits imposed by AirMap.

Collect rulesets from briefing

Add flight plan deletion

Moved flight planning away from "Flight Management" to its own class. Planning does not need a connected vehicle.

AirspaceManager is now exposed by QGroundControlQmlGlobal instead of Vehicle (available all the time)

* Also handles correct prioritization of high latency links

Plus various bug fixes from flight testing

Also remove custom gimbal support

And fixes they found