Tweaks to toolbar visibility

VIsual tweaks

Added configurable value grid to toolbar

Re-architect toolbar for better customization capabilities. Also use less real estate.

Programmatic switch to SetupView leaves two buttons selected

Prevent view switching apis support a stack

View switch prevention support

Restructure toolbar to make it Flickable

Fix spacing

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.