Changed: tapping the app icon opens the clock again. It opened the settings
because a badly chosen picture could make the full-screen clock stop answering,
and the settings were the only way back to undo it. The app now notices that
case by itself — a start that finds the previous run's mark still set opens the
settings and loads no pictures or imported fonts — so the door no longer stands
in the way of every launch.

Changed: long-pressing the app icon offers "Settings" on Android 7.1 and newer,
which goes straight there without starting the clock.

Changed: "Show a calendar on the clock" is now the first thing on the time and
date screen.
