Merge branch 'parse_entity' into 'master'

arkindex/documents/api/ml.py

arkindex/documents/fixtures/roles_transkribus.yml

arkindex/documents/pagexml.py

arkindex/documents/tests/pagexml_samples/create_blocks.xml

arkindex/documents/tests/pagexml_samples/create_entities.xml

...x/documents/tests/pagexml_samples/first_and_last_name.xml

arkindex/documents/tests/pagexml_samples/merge.xml

arkindex/documents/tests/pagexml_samples/regroup.xml

arkindex/documents/tests/test_pagexml.py