Compilation fixes for Windows

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.

Merge branch 'integration_merge_connstatus' of github.com:Susurrus/qgroundcontrol into integration_merge_connstatus

The QGCUnconnectedInfoWidget now remains square and has more rounded edges so that it looks more like a button.

Finished merging QGCVehicleConfig.ui, which I hadn't done properly last night. Things are now in a usable state again.

Conflicts:
	src/uas/ArduPilotMegaMAV.h
	src/ui/uas/UASListWidget.cc

Conflicts:
	src/uas/ArduPilotMegaMAV.h
	src/ui/uas/UASListWidget.cc

Conflicts:
	src/ui/QGCVehicleConfig.cc
	src/ui/QGCVehicleConfig.h
	src/ui/QGCVehicleConfig.ui
	src/ui/uas/UASControlWidget.cc
	src/ui/uas/UASListWidget.h
	src/ui/uas/UASQuickView.cc

Changed many functions in the abstract *Link classes to be const. This facilitates setting other functions as const. The metadata for specific links are reset when the links are added.

The details on the success/errors for the MAVLink protocols are now shown for each link as tooltips that are updated every 5s. Values are currently wrong and unsure why as of yet.

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.

Update README

Removed OpenGL dependency in HUD, merged in HUD from Soren Kuula and config changes from Michael Carpenter