Add networkx support

[psychemedia]

Install and demo packages that support conversions between neo4j and networkx graphs. For example:

• https://neonx.readthedocs.io/en/latest/
• http://www.solasistim.net/posts/neo4j_to_networkx/
• https://neo4j.com/graphconnect-2018/session/networkx-api-graph-algorithms and https://github.com/neo4j-graph-analytics/networkx-neo4j

With graphs returned from noe4j queries cast into a networkx representation, we can then visualise them using networkx visualisation tools, including things like netwulf.