Tweaking MapType and MapCenter icons
Added Zoom Plus/Minus icons to be used for maps
Added PiP icon for the upcoming Picture-in-Picture functionality

Plus more overall ui work

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

- Only show video option if supported
- Persist settings
- Show/Hide/Add items correctly

- Restructured a number of MissionItem properties as well

Plus lots of other cleanup

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