[NEW FEATURE] NGC masks

[martinkilbinger]

Some NGC objects are large, closeby galaxies, which should be masked.

E.g. this is a zoom-in of the shape catalogue of P7:

Some NGCs are too small and/or faint to cause problems, some are included in the Messier catalogue.

The rest should be masked.

[martinkilbinger]

Checked again, there are 7840 objects in the NGC. The catalogue we provide with the pipeline has all those, and an additional 3866 objects from the IC II (Index Catalogue lI, update to NGC from 1908).

So this should be a pretty complete list of NGC(+) objects. I think we can close this PR.