UI Tweaks for all mobile platforms.

* Remove leftover debugging message
* Fix segfault on Linux at close for #3164

- Also fix vehicle selector dropdown in toolbar

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

Now I'v discovered a Slot that returns a bool, this is not very
good because Qt expects a slot to have the same return type
as the signal, void, always.
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

that was connected to showNormal, which always led to a smaller
minimized window irrespective of whether the applicaton was
full screen or not. Now it checks and always returns to maximized.

- 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

Instead us a Toolbox concept which hangs off of QGCApplication