_save_input_files_controlprofinp does not allow empty "Trace gas replacement profiles"

For my use there is no need for Trace gas replacement profiles. In Sciatran, an input of "0" as first line for this parameter is allowed, so it would be great to have this opportunity in pyatran, too. (Dirty solved the problem for me by adding a trace gas which does not interfere with our wavelength region of interest)