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)

Empty for new

Is this going to fix errors with different versions of networkx? I don't
know -- I'm on a plane mate.

- `GraphState.copy()`
- `measure_x` etc.
- `measure(detail=True)`
- Better documentation on `remove_vop` and `act_local_rotation`

Looks like nondeterminism in `next(d.iterkeys())` was breaking
consistency with A&B. Next up: switching determinism on or off.

Had a dumb translation error

Some tests are disabled and forcing outcomes does not work

Dunno why it was ever `complex`

It's kinda ghastly at the moment. But lots of obvious improvements.

Added some more terms to clifford.by_name to ease lookup of complex
conjugates

Added GraphState.toggle_edges(), used by GraphState.measure_x

Nearly finished GraphState.measure_x