- add multi-vehicle support: each vehicle has now a per-vehicle AirMap
  object that takes care of flight creation, traffic & telemetry
- add a base class API layer so that the interface between QGC and the
  AirMap implementation is clear, and easier to change
- removes polygon upload to vehicle (needs a better solution)

Also fixed bug with ArduPilot guided waypoint write which would trash
existing mission.

Remove/comment off debug output pollution

This time to handle correctly updating plan/fly view when plan changes

Works around ArduPilot strangeness with empty missions end

Must memset structures before use.

Fixed a pile of bugs as well

Plus low battery announce changes

Retry in all the right/possible places. Don’t freak out about things
coming in unknown sequences.

_finalize methods need information which is not available if all you
have is a mavlink_message_t

Includes ability to load params

- GeoFence support comes from plugin
- Circle fence support
- Better param support