Minor README tweaks. [ci skip]

Making tile cache description not mandatory.

Sensors small screen

Offline map small screen

Fix icons for iOS.

Restoring link change signal.

Camera: Small screen fixes

Safety: Small screen fixes

Flight Mode: Flow sections to available real estate

appveyor install gstreamer

Removing unused signal.

Radio: Small screen fixes

Update map URLs

Advanced Flight Mode: Small screen updates

Simple flight mode small screen

Remove unused code

Safety: Hide icon on small screens

Power small screen

General setting sizing