Increasing # of substamps

[arminrest]

The catalogs of image and template are used to get a good list of substamp candidates. Due to the masking, lots of these substamp candidates are rejected since a masked pixel is in the substamp. For sparse fields, this can lead to an unsufficient number of substamps. Fix: if a substamp candidate is rejected, check if the substamp is
acceptable if the center of the substamp is slightly moved (The object does not have to be dead center in the middle of the substamp!).