App messages now use simple modal message dialogs. Vehicle messages continue to use non-modal popup.

The VideoReceiver should work 'as is', without depending on the
whole application or in the settings. This patch removes all the
hard dependencies on QGroundControl, FactSystem and Settings system
so it's easier to isolate and test the code.

UI tweaks

Disable closing app on last window close. This will close
the app on every widget spawned in QML that closes (MessageBox)

Revert QGuiApplication->QApplication change since it breaks message dialogs.

Remove duplicates from missing parameter reporting

Plugin'ized follow me support

Automated the generation of language resources into the application
Added all languages that come from Crowdin, even if empty.
Allow dynamic language changes

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

Get rid of QGCView, QGCViewPanel and FactPanel. All messages and dialogs are now handled in the root window.

Move cache location methods so they are available in all builds

Add support for specifying fixed RTK base position

Stable desktop version check

Remove unused code

Also hand carried text to speech changes from Stable to master. Plus
unit tests for that.

Switch test from 8.8.8.8:53 to "www.github.com:80"

Signed-off-by: Patrick José Pereira <patrickelectric@gmail.com>

No more user prompting

Convert bool settings to SettingsFact

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