updates to relphot to support ubercal, distributed dvo; some optmimization (eg, image matching to area); cleanup names of static helper arrays in ImageOps, MosaicOps; cleanup rules for -reset options (relphot does not reset astrom bits); add flat-field correction; determine ubercal distance for images; better plot ranges; bcatalog limit density selecting objects by number of measurements; allow relphot to update the output catalog schema (catformat); make relphot -averages and relphot -update-objects equivalent in how low-quality objects are handled; record stage at which average is determined