People may want to rerun SOAP on a simulation for which they already have a SOAP catalogues with SOs computed. It would be useful if SOAP could take a SOAP file as input, and use the SO radii from that file, rather than having to recompute SO radii for the new run.

Currently we have to calculate bound subhalo properties (to get the number of particles of each type for the filters). We could also skip this step if we are rerunning SOAP