Small update to Subgraph API in `rel2graph.neo4j`: Properties that don't exist now return None. Fixes for 21.
1.3.1
New API functions "keys" and "update"
1.3.0
This release fixes a major issue with concurrency. Under specific circumstances it could happen that relationships are lost during the conversion process (see issue 20). With this release this no longer happens. Both CREATE and MERGE are now serialised. Comes with slight performance hit.
1.2.1
Renamed "type" parameter of rel2graph.neo4j.Relationship to "relationship_type" to avoid naming conflicts with Relationship properties.