tools using singularity

• https://training.galaxyproject.org/training-material/topics/dev/tutorials/containers/slides.html
• https://docs.galaxyproject.org/en/master/admin/special_topics/mulled_containers.html#build-singularity-containers-from-docker-containers
• https://depot.galaxyproject.org/singularity/
• https://github.com/galaxyproject/planemo/issues/922#issuecomment-483996788