Use residents notifications for better gnome shell/plasma compatibiliy

Here a patch adding residents notifications support for clementine.

This make the desktop shell not open a new notification when a previous one is open.
Does that mean the notification will remain visible until the user close it?
(That's my understanding of https://developer.gnome.org/notification-spec/)
If so, I'm not sure this is good, as this might bother some users who would expect the notification to disappear after a short amount of time.