'Change the nickname for a member of the group conversation and displays
this change to the user.
@param oldnick: The old nickname.
@type oldnick: C{str}
@param newnick: The new nickname.
@type newnick: C{str}'

def memberChangedNick(self, oldnick, newnick):

    if (oldnick in self.members):
        self.members.remove(oldnick)
        self.members.append(newnick)
