This allows for better multi-vehicle testing

* Map type now set from General settings
* No map type control in maps

Convert bool settings to SettingsFact

* Holds all the settings for the app
* Allows core plugin to override default values

Prevent shutdown ordering crashes

Made QGCCorePlugin derive from QGCToolBox and expose everything through the same mechanism as everything else.

_finalize methods need information which is not available if all you
have is a mavlink_message_t

Move battery.percentRemainingAnnounce to Qml Global

The static Fact was causes problems with Qml

offline mission planning settings

more conversion stuff

some fixes and added area unit drop down

Conflicts:
	src/MissionEditor/MissionItemStatus.qml

removed comment

finish unit conversion

correcting typos