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.

Added angle conversion testing, added battery settings option, added option to set MAVLink ID of groundstation

 Changed for a simpler way unit tests can be set up and run. Now tests can be simple classes which implement the tests