Merge branch 'encyclopedia-api' into 'v0.8.1'

nomad/app/api/__init__.py

nomad/app/api/encyclopedia.py

nomad/atomutils.py

nomad/client.py

nomad/datamodel/datamodel.py

nomad/datamodel/encyclopedia.py

nomad/datamodel/metainfo/public.py

nomad/datamodel/optimade.py

nomad/metainfo/__init__.py

nomad/metainfo/elastic_extension.py

nomad/metainfo/example.py

nomad/metainfo/legacy.py

nomad/metainfo/metainfo.py

nomad/metainfo/search_extension.py

nomad/normalizing/band_structure.py

nomad/normalizing/dos.py

nomad/normalizing/encyclopedia/basisset.py

nomad/normalizing/encyclopedia/encyclopedia.py

nomad/normalizing/encyclopedia/material.py

nomad/normalizing/encyclopedia/method.py