Add ptsrc=no option to config file

[cdeil]

Faissal is producing light curves with 100s of bins, resulting in many 100 GBs of files.

The question is how the file sizes can be reduced.

One option we were thinking of was passing ptsrc=no to gtsrcmaps, which produces the larges files (200 MB per time bin).

Or maybe add an option to remove intermediate FITS files once a time bin is finished processing?

@zblz @davidsanchez What do you think?