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

Refactored QGC startup so that MainWindow::instance() is usable everywhere. This was required to get the styling working properly for ChartPlot.

Moved all shared code for IncrementalPlot and LinechartPlot into a common ChartPlot superclass. Also recoloring the background of both widgets now works when switching between color schemes.

The light and dark style sheets are now self-contained instead of only coloring. Both the have been synchronized, though the light style sheet still needs some adjustments.

HIL config improvements, fixed confusion about which dock widget is part of which view, main window behaving now

Segregated the coloring of the UI from the rest of the styling in the CSS, so now style-base.css is loaded before the colorizing CSS files.

Removed the ICONDIR token from the CSS styles; it wasn't necessary and slowed down applying new styles to QGC.

Hotfix: Fixed widget / UAS initialization order which led to text messages (and other updates) being ignored if the widget was not open when the UAS was created

Selecting the desired stylesheet now works correctly, including saving settings between application launches.

Reworked the styling UI. Now there are 4 options: light, dark, custom_light, and custom_dark. Things don't quite work right, but the proof-of-concept is done.

Change so Waypoints are the same across maps, and offline waypoints get appeneded to the end of the MAV's waypoint list on connect

Added satelliteCount to the QuickView, and made quickview a default display on the mission planner view.

Change so mission view is default instead of unconnected, fixing a bug causing misloading of tool widgets

Additions for View navigation, including saving dockwidget locations and status. Also added remembering of "Advanced Mode" between restarts of QGC

Changes for the new "View" navigation, and fixes to get most of the dockwidgets working with the new view system

view, rather than having universal dock widgets.