GitLab

Docker image building added

Remove esutil dependency as it causes unpredictable errors on installation, and has only been used for spherical matching. Now we have a drop-in replacement for that.

Documentation for pre-processing images, including stacking them. Also, simple example notebook for image stacking.

It is anyway bad as it means the code is run incorrectly or SExtractor failed, but at least we should not add our own crash on top of that!