D-Net

#577 introducing UDF producing empty map, two transformers building common Citation datastore from citationmatching and pmc ingestion outcome. Both are required by collapser.

introducing importer/plaintext/skip_extracted transformer required for plaintext import caching

#354 removing obsolete transformers/export/person transformer along with tests

#354 removing obsolete transformers/export/inferenced_document_without_imported_data transformer along with tests

#354 removing obsolete transformers/export/identifier/referenceddatasets transformer along with tests

#354 removing obsolete transformers/export/identifier/documents transformer along with tests

#354 removing obsolete transformers/export/document transformer along with tests

replacing redundant transformers/ingest/pmc/citations with already existing transformers/importer/documentmetadata/idextractor

replacing redundant transformers/ingest/pmc/citations with already existing transformers/importer/documentmetadata/idextractor

replacing redundant transformers/ingest/pmc/citations with already existing transformers/importer/documentmetadata/idextractor