- 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)

Make AirMapController as part of a Vehicle rather than a creatable QML instance. This is ultimately linked to a vehicle and not the view. Eventually a lot of the code currently in AirMapManager will have to come here as well so the data persists with a vehicle. AirMapManager should only handle the global aspects.
Added a temporary indicator right below the toolbar. It's only visible if a permission (of any kind) exists. I need to understand better how this works before coming up with a more permanent solution.
Restored toolbar to its original state (brand logo and whatnot)

Added AirMap settings (SettingsGroup)
Added AirMap settings block to General Settings
Create macros to deal with the tedious repetitions within SettingsGroup
Removed old, hacked in setting for AirMapKey
Remove a few of the tons of build warnings

Nope, it's microseconds alright. The autopilot I was testing with indeed only had 19 seconds of "armed" time.

Also hand carried text to speech changes from Stable to master. Plus
unit tests for that.

Still does not support multi-vehicle

Fix merge issues

Switch only to MAVLink 2 on first connected link. Fall back to v1 if two links to the same vehicle are connected and one can only do v1

This extension introduces a complete version handshake mechanism which will detect wether the vehicle AND the complete link / routing infrastructure support MAVLink 2. If they do, QGC will switch to the highest protocol version supported by all connected vehicles. If a new vehicle connects, it will re-negotiate the highest possible version. This means that we error on the side of compatibility, which later can be easily changed.

Remove/comment off debug output pollution