fixed exact search, fixed permId search bug
fixed entity_type caching problem
various bugfixes
fixed problem with highly connected samples and datasets
fixed bug in extract_identifiers
many bugfixes, implemented where statement
now compatible with git-annex 8.2
added mass deletion to transaction
fixed del_parents() bug accidentally introduced in 1.18.0
added many additional search features
fixed vocabulary update, extended documentation
fixed saving vocabularies bug(s)
fixed vocabularies bug