That factor of two is criminal.

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

Made sure that `graph.js` dumps old graphs after use, and ensured that
`examples/stress_test` shuts down the connection after use (don't create millions
of clients).

Next up: measurement
Also added a test on local complementation