v2.2.0

1. Add option to specify number of play queue tracks for dynamic playlists.
2. Add option to set application style.
3. Fix potential issue with priority menu items being disabled.
4. When adding items with a custom priority, or updating a custom priority, add option to have this priority decrease with each item.
5. Remove unity menu icon work-around.
6. To support older GNOME settings daemon installations, if fail to use the new MediaKeys DBUS interface then use the previous.
7. Fix desktop detection via XDG_CURRENT_DESKTOP - check for colon separated values.
8. If an error is to be shown, ensure Cantata is not minimised to system tray.
9. If the initial start-up connection fails, try again every .5 second for a few seconds.
10. In playlists page, internet, etc, allow back navigation to go fully back.
11. Don't try to seek if no song loaded.
12. Only use menubar for macOS builds.
13. Smart playlists - like dynamic, but do not auto update.
14. Use em-dash to as separator.
15. Add device option to only transcode if source is FLAC or WAV (detection is solely extension based).
16. Fix extraction of album names from DB - for use in tag editor and playlist rules dialogs.
17. Fix some potential security issues - thanks to Jonas Wielicki for the patches.
18. Only set Qt::AA_EnableHighDpiScaling for Windows builds.
19. Fix sidebar highlight for windows (at least for Windows 10).
20. Only enable system tray for Linux if org.kde.StatusNotifierWatcher DBUS service is registered.
21. Fix MPRIS track path.
22. Fix MPRIS can go next/previous state changes.
23. When playing MPD's HTTP output, stop backend when MPD is paused.