We need intermediate save points during calibration #226
Description
I have lost several days to calibration erroring at various points after the degridding and per frequency calibration steps. One of these was an x-forwarding issue where I had just ssh'ed without the -X parameter. When I restart FHD I have verified that I have all recalculation keywords set to 0 and yet it seems that it has to go back through both degridding and the per frequency calibration minimization routines, which take >12 hours in my case. We need to be saving out the results of these time-intensive steps immediately after they happen so that they do not have to be recalculated because of simple plotting issues.