Also remove Move Up and Move Down support

This is in preparation for full Qml main window

Also understand the concept of missions which cannot be edited

Plus more overall ui work

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

- Restructured a number of MissionItem properties as well

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

Everything is now based off of default font pixel size