Graph reference

This module allows you to create a mathematical graph of entities.

Use cases:
- By using this module to create graphs of taxonomy term references, you can get a lot more information about the relationship between different terms in the graph and about the graph as a whole.
- You can create an equal two-way relationship between entities (no parent or child, just neighbors).
- You can add entities of all types to a graph.
- You can check if the current graph is circular, tree or connected.
- You can put a constraint on the graph to force one of the above graph types.

Required modules:
- dynamic_entity_reference