These use OpenGL implementation which prevented moving to ANGLE
support. Since they are rarely used they are being remove instead of
being upgrade.

- New MissionManager
- Plumb MissionManager through MissionEditor
- Mission Editor supports get/set

Plus lots of other cleanup

- Moved all MavManager functionality to Vehicle
- Updated all code to use Vehicle instead of MavManager
- Removed MavManager

- MultiVehicleManager is a Qml friendly replacement for UASManager
- Vehicle is a replacement for both UAS and AutoPilotPlugin

- FirmwarePlugin is the new place for code which is specific to
firmware flight stack
- FirmwarePlugin currently supports flight mode apis
- Modify code to use new FirmwarePlugin support

Usability plus, new features:
- 3DR Radio support
- APM Stack support

Everything is now based off of default font pixel size

Sorting source and headers while at it.

Initial rendering of Waypoints