Moved that functionality into `abp.GraphState`, so that you can just run `state = abp.GraphState(nx.Graph(((0,1),)))`, `state = abp.fancy.GraphState(nx.Graph(((0,1),))` or whatever.
Now you can write `abp.fancy.GraphState(nx.Graph())`. TODO: make this work for a non-fancy `GraphState`
Trying to get more sensible defaults for people who like to think about graphstates rather than circuits. Repsponse to issue #4: [Link](https://github.com/peteshadbolt/abp/issues/4)