Make graph reference singleton?

[theengineear]

There's a funny dependency issue:

1. on first init, config may not be set...
2. config gets set in tools
3. tools requires graph reference
4. graph reference requires a plotly domain from config... :(

This might be alleviated if we can make the GRAPH_REFERENCE a singleton which isn't actually created until it's used. This will be tricky because graph objs can't be instantiated until later for this to work...

[jonmmease]

No longer applicable to version 3