Sets the server group to <name> for the window. ircII will attempt to always keep windows with the same server group name connected to the same server. i.e.: If you set up windows 3, 5 and 6 as being in server group `foo', (with the
WINDOW ADDGROUP foo
command) then, when one of these three windows are connected to a server, the other two are also connected to this server.
See also window/delgroup