Fix type error in CL-STOMP:START (issue 1)
The function calls USOCKET:WAIT-FOR-INPUT and expects the result to be a list. Unfortunately, USOCKET:WAIT-FOR-INPUT has an optimisation, which makes it return its first argument as-is under certain conditions. Since START passes a single socket directly (not wrapping it into a list), WAIT-FOR-INPUT returns that, causing a subsequent CAR call to fail.