Restore QGC to its normal UI layout (buttons on toolbar)

TODO: Improve the experience

Prevent clicks going through top level items

For showTouchAreas and showAdvancedUI

* Make MainToolbarIndicators reusable by other views
* Change to font based ratio sizing

* Vehicle selection must be global control
* Disconnect controls must be associated with Vehicle

Made QGCCorePlugin derive from QGCToolBox and expose everything through the same mechanism as everything else.

Also removed intermediate param load retry message

Also added new FirmwarePlugin::brandImage support