Ticket #24 (closed enhancement: fixed)

Add some more badges to the icon of the application in the dock to illustrate its state. We could add the following ones when the application isn't the frontmost app:

• Number of untouched incoming chat windows that have popped up;
• Total number of unread messages in all open windows combined;
• Some small icon to signal that a file transfer has completed;
• We could also allow the file transfer speed to be displayed, but it would be optional.

We should discuss what is to be shown, since there are a lot of options.

(migrated from #154)

Refs #76, #96