Improvements
- The click sound can now be customized (note duration and beat/accent note pitch) in a dedicated settings dialog.
- File import/export now uses standard JSON format. Unfortunately exports made with previous versions of the app will not work.
- Home UI layout reworked to fit smaller screens (< 5") better.
- When metronome is running, a status bar notification is shown.
- Code cleanup/refactoring

Fixed
- Various UI bugfixes
