* 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!

* Add support for another board

* Added a 2nd custom board

3DR Radios no longer exist

Domain changes for the ArduPilot locations from DIYDrones to
ArduPilot.org

I removed some needed headers from a top level file which then causes a
ripple effect downstream

Removed commented v4 ArduPilot Quad fw links

To address issue https://github.com/mavlink/qgroundcontrol/issues/2735

- Also fix vehicle selector dropdown in toolbar

Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Even though it’s wrong!

- Pervasive change to automatically connect to known board types
- Lots of additional changes along with this:
- More exposure of objects/properties to Qml
- Much restructuring in LinkManager and LinkManager clients