Suggestion: to restrict the channels dumped by gwl-print-channels to those actually present in the frames at the GPS time of interest

Browing some VirgoDQR outputs, I've noticed that sometimes the Omicron full scans do not process successfully all channels. Digging further, this happens when an unlock follows quickly the trigger t_0 and the channels for which Omicron reports a failure include all the ALS channels that are only part of the DAQ when they are needed, that is during the initial phase of a lock acquisition. I think that happens because gwl-print-channels scans a 100-second frame file that contains both the trigger t0 and some later unlocked data. If that assumption is correct and if this is technically feasible, I would suggest adding a command line option that forces the executable to only dump the names of the channel that are present at t_0 / in the frame containing t_0 / in all the frames of the frame file (whatever is the simplest / best option).