Full coverage of Neo4j write operations supported by ROM commands

[maetl]

Need to ensure there are commands which cover the full range of standard features in cypher in a generic way.

• Generic create command (?)
• Generic update command (?)
• Generic delete command
• Create node command
• Create edge command
• Update node command
• Update edge command
• Delete node command
• Delete edge command
• Transactions?
• Create graph command which composes nodes and edges (?)

The last point could be done as a command pipelining example rather than a supported command class. But would be a good idea to work towards a use case involving a more complex create or update of a connected subgraph.