New functions handle creation of new graphs (and directed, etc.).

A directed graph - has a list of directed edges.

DirectedJsonGraph is explicitly a directed graph.

A standard Json graph - has a list of edges.

The graph base has attributes shared across graphs.

A JSONGraph can either be parsed into a list of graps or single graph We have types for standard, and then explicitly directed and undirected.

An undirected graph - has a list of undirected edges.

UndirectedJsonGraph is explicitly an undirected graph.