* Fix minor spelling error

* Added support for the AUAV x2.1 Flight Controller
    also removed a duplicate entry for MindPX
    from src/comm/USBBoardInfo.json

Adds entries required to correctly identify, download and flash PX4
firmware to the AUAV X2.1 Flight Controller

* Update USBBoardInfo.json

Removed un-needed fallback entries. This has been tested!

And fix broken file path to save video on windows

Other minor formatting and stability improvements

- Shot Interval in Survey
- Much change to time/distance calc

Even though it hasn't been supported forever, the files where still
being compiled

Prevent shutdown ordering crashes

* Make MainToolbarIndicators reusable by other views
* Change to font based ratio sizing

This prevent the visibility change from trashing source setting

Shows horizontal/vertical scroll indicators

* Vehicle selection must be global control
* Disconnect controls must be associated with Vehicle

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

Also removed intermediate param load retry message