v4.7.0:
- Improve synchronization between sound and visual feedback and vibration
  (thanks to TBWarrington and jorfus for all the testing)
- Remove notification more reliably, when app is killed.

v4.6.1:
- Fix crash after pressing play on some systems
  (thanks to jorfus for the support to find the issue)
- Fix playing first note twice after pressing play on some systems
  (thanks to jorfus for the support to find the issue)
- Modified mute icon
- Updated to latest dependencies
