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

- Convert mission load/save to it
- Allow parameter load/save on mobile

Also additional major Mission usability changes

Instead us a Toolbox concept which hangs off of QGCApplication

- Delete all old map code

This allows for testing issues found on high dpi screen without needing
a high dpi screen. it does this by doubling the font sizes.

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

Moving methods from MainWindow to QGCApplication so that more things
can run without a window. Helpful for testing.

Allows for UI unit tests to be written:
- Ability to respond to expected message boxes
- Ability to fail test if unexpected message boxes occurs