Merge branch 'f-versioning' into 'dev'

.gitlab-ci.yml

CHANGELOG.md

README_SETUP.md

doc/table_structure.md

makefile

patches/patch20200710-3.0.0-rc2/feature_config.sql

patches/patch20200710-3.0.0-rc2/fix_unversioned.sql

patches/patch20200710-3.0.0-rc2/patch.sh

patches/patch20200710-3.0.0-rc2/versioning.sql

procedures/deleteEntity.sql

procedures/deleteEntityProperties.sql

procedures/deleteIsaCache.sql

procedures/entityACL.sql

procedures/entityVersioning.sql

procedures/insertEntity.sql

procedures/insertEntityProperty.sql

procedures/insertIsaCache.sql

procedures/registerSubdomain.sql

procedures/retrieveEntity.sql

procedures/retrieveEntityOverrides.sql