- also here don't use client.url to figure out if a session is open
as that doesn't work in FF
- use tag to make sure we're dealing with the right type of notif
- use findClient function
- use event.waitUntil to prevent default notification
- replace notifications for same room
- replace notifications when receiving unread=0 with "Read messages"
to prevent default notification
- don't rely on client.url to figure out if a room is open as FF
does not update this field on hash changes.
