Fixed bugs the unit test found

- 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