Syntax:
c_announce(msg, interval, category)
To send a one time announcement: c_announce(msg)
To repeat a periodic announcement: c_announce(msg, interval)
To cancel a periodic announcement: c_announce()
To add only icon: c_announce(msg, nil, category)
Example:
c_announce("Hi all!", nil, "vote")
List of all known icons: vote, resurrect, death, join_game, leave_game