Dark Mode: adapt to new Android API

Android 10 now propose a System mode that should replace the legacy Day/Night.

Only 3 choices should be proposed depending on the Android API:

• Android 10: System/Light/Dark
• Older: DayNight/Light/Dark

Furthermore, clicking on the DayNight button from the first start menu switch to light mode, even when your system is configured for Dark, and without any feedback from the application.