Removed incorrect Vehicle.altitudeWGS84

Plumb through initial object mode on Vehicle

Also additional major Mission usability changes

Added conditional statement to disable the virtualTabletJoystick output if a real joystick is connected and enabled. Without this, two different sets of values would be sent and would appear highly sporadic.

Also, added a missing method on AutoPilotPlugin as a public
pure virtual method (the inheritances already implemented it as a
slot, so the new Signal syntax didn't worked because the base class
didn't had that method)
Signed-off-by: Tomaz Canabrava <tomaz.canabrava@intel.com>

Windows OS doesn’t disconnect port when you pull plug on USB. This
caused all sorts of problems with previous logic. New logic handles
this correctly.

- 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