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.

Conflicts:
	src/ui/MainWindow.cc

Fixed some display of parameters where no vehicle-specific config is specified

Fixed setting the slider position based on parameter values for variables that don't have a range specified.

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.

Further styling changes to the outdoor stylesheet. The indoor sheet was modified as inline styles are removed from the C++ code.

Some .ui files still pointed to an old mavground.qrc file. They now point to the proper qgroundcontrol.qrc file.

Removed commented-out references to setStyleSheet(). Moving towards all styles being set in .css files

Added missing separater to Tool Widgets menu.