make sure IvitationBuffer.shutdown() does not raise

darcs-hash:20081125092246-b2873-d1e1c800c36614ce9cf18af3dd4b2530a0b70536
consolebuffer: made copy_input_line to accept optional 'line' parameter

darcs-hash:20081125093043-b2873-d5822c13519382f0061b1648a18b51e23441aab5