If a room doesn't have a set icon (and it isn't a one-on-one chat, for
which the icon'll come from the other user's avatar), the default icon
is now determined based on user count.
If there's X users, an icon with X people will be displayed, up to four.
After that, a "+" is overlayed on the icon.
Not really necessary… but I think it's cute. :-)
Jaidyn Ann