Merge branch 'CI_for_PLWN_API' into 'master'

.gitlab-ci.yml

plwn/__init__.py

plwn/_loading.py

plwn/bases.py

plwn/enums.py

plwn/exceptions.py

plwn/readers/comments.py

plwn/readers/ubylmf.py

plwn/readers/wndb.py

plwn/readers/wnxml.py

plwn/relresolver.py

plwn/storages/objects.py

plwn/storages/sqlite.py

plwn/utils/graphmlout.py

plwn/utils/sorting.py

plwn/utils/tupwrap.py

tox.ini