Prevent shutdown ordering crashes

* enable TCPLinkTest
* enable FileManagerTest

- 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 turn on MavlinkLogTest

Instead us a Toolbox concept which hangs off of QGCApplication

Also many LinkManager API changes to further isolate all link
management inside LinkManager.

Plus a large number of other changes to allow for orderly shutdown of
objects without crashes or asserts. This is need for unit tests to
create/delete global state around every test.

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

Destroyed signal must have been working incorrectly in the past.

Added a unit test, setAirframeTest. Changed setAirframe function. Added an end_of_enum to the airframe enum.

I had to update some method calls in UASUnitTest.cc. I'd bet that some of the tests are wrong now because of it.