Custom, single firmware upgrades were fixed to "stable", even if the user selected "custom".
The code, when selecting the firmware type was using the combo box model index instead of the actual type defined by the list model.

This adds support for the full-sized FMUv4PRO design and the FMUv5 STM32F7 based generation.

* 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

- 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

- 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

- 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

Also enable identification of clone 3dr radios

Usability plus, new features:
- 3DR Radio support
- APM Stack support

Also updated parser for new xml format

- Much simpler UI
- MVC style qml programming model

QSerialPort buffering too slow on Windows.