[daip] Flagging of many bad points

[Johan van der Walt]

When making a UV plots for the primary and secondary calibrator sources
I noted that there are quite a number of points that lie well below the
majority of points. 

Can one flag all these points in a multisource file with one run of
UVFLG? From the EXPLAIN of UVFLG it seems to me that one cannot clip
points below a certain value in a multisource file. 

Thanks

Johan