Now works for more than Serial links

This function is called automatically when a QSettings object is destroyed,
so is rarely needed to be called explicitly.

There are still some cases where
a QSettings object is passed-by-reference, so there I left the sync() calls as
it's unclear how permanent those objects are and if they'd call sync() before
application shutdown

also adds AMSL output in ft

Another change for issue #3, SerialLink::getCurrentPortS() should now return consistant results on Windows to match linux and OSX

Fix for apm_planner issue #3, Serial port handling of '-' characters, since OSX can have a '-' in the port name

Fixed styling of the toolbar, specifically coloring and sizing of the buttons, and made the labels aware of the current window theme. Also made some changes to updating the toolbar when switching UASes or when UASes disconnect/reconnect.

Removing UASes now returns the UI to an almost pristine state. This was done by altering the activeUASSet signal so that it can emit a NULL UAS. Crashes may still exist in autopilot-specific code.

Partway through refactoring of UAS deletion. This is in order to actually support removing UASes from QGC, which is currently impossible.