Messy logic for notifications sending

[KitsuneRal]

The way it's done is handling a signal when the number of highlights changes and making a notification if the number is more than 0. First off, this misses on the case when the room with the notification is already on the screen - there's no point in making a notification in that case. Second, it can miss notifications when the number of highlights doesn't change due to one new highlight in and one old one out.