Merge branch 'f-entity-getters' into 'dev'

CHANGELOG.md

src/caosdb/__init__.py

src/caosdb/apiutils.py

src/caosdb/cached.py

src/caosdb/common/administration.py

src/caosdb/common/models.py

src/caosdb/connection/utils.py

src/caosdb/utils/create_revision.py

src/caosdb/utils/get_entity.py

src/doc/conf.py

src/doc/tutorials/Data-Insertion.rst

src/doc/tutorials/Entity-Getters.rst

src/doc/tutorials/caching.rst

src/doc/tutorials/first_steps.rst

src/doc/tutorials/index.rst

unittests/test_cached.py