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

The light and dark themes now use slightly different blues for their accent colors that is higher contrast.

The background color of the mission items is now controlled by stylesheets as well. This change also fixed restyling the mission lists when a style change occurred.

Reworked the UAS listing. It's organized differently and styled differently. Also the fading of the heartbeat status now works properly. Also fixed some theming issues with the connectButton when it was checked.

Synchronized the dark theme to the changes to the light theme from the last commit. Also made more text change color based on selected theme.

Extended most of the new toolbar theming to the dark theme. It looks pretty good, though both themes still need some more refinement.

The toolbar now displays much nicer under the light theme. Also colorized the connect/disconnect & delete buttons in the communications settings window.

Whoops. Look like you can't inherit from QToolBar using Qt Designer. Restored last set of code. Also, changed one of the QToolButtons to a QLabel in QGCToolbar.

Reduced the QDockWidget's border down to 1px wide. Annoying to have 10px border on the widgets when they were floating.

Removed the UnconnectedUASInfoWidget class as it could be replaced with a simple QLabel with the same functionality. Also styled the NO UAS warning on the ReadOnly mission view so it looks good in both dark and light themes.

Switched button coloring so they're default grey with a :hover of blue instead of the other way around.

The View Only waypoint view is now styled similarly to the editable view. Same caveats apply where the widgets don't update their style if QGC has its styles changed.

The editable waypoint view has been completely reworked from a styling perspective. Now both the light and dark styles work great, though switching between the styles doesn't work as expected yet. That's still to come.

Further refinements of both the dark and light themes. The light theme is about 95% done, though the dark needs some more work.

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.

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.

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