Flight management with date range, delete flights.

Cleaning up old vehicle manager and getting it ready to actually provide services for a vehicle (flight management)
Added submit flight plan
Added update flight plan
Disable flight features as these don't seem to be quite working (values must be initialized and validated before submission as backend doesn't validate and the objects don't initialize their members)

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)

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