v0.4.15 — The app now tells you when a new version is out

• Installs from a downloaded APK, F-Droid or a mirror had no way to learn a newer version existed. The app now checks once a day and shows a dismissible banner when one is available.
• "Not now" is remembered for that version only.
• Settings now shows the version you are actually running instead of a hard-coded placeholder.
