Notification dot in favicon

[Christilut]

The favicon is static currently and does not change. It would be very useful if the favicon would change if there is new assigned conversation. If you pin a tab then it only shows the favicon so then it would be most useful.

Optionally it might also be an idea if instead of a simple dot, it would be a number to see how many pending conversations there are. Similar to how GMail does it.

This is a tiny but (I think) very useful addition.