The detection limit of the image for clumps and objects is now
reported in the output of MakeCatalog. In order to do this, I had to
save the S/N thresholds in NoiseChisel to header keywords in the
NoiseChisel outputs. MakeCatalog then reads those headers and makes
the information. The manual also contains a complete explanation.

I also had to update the old "readkeyword" function in fitsarrayvv.c
to "readkeywords". Now it can read as many keywords as the user wants.