Opensurfacesim

Another update with fixes following the v.0.1.1 PyPI release.

* Support for the [Qt5Agg](https://pypi.org/project/PyQt5/) backend for interactive plotting.
* Fix for static forest generation in the Union-Find decoder
* Fix for legends not properly showing
* Fix for redrawing of temporary changes to plot objects

For IPython, the GUI of the Tkinter backend is not available. The included `examples.ipynb`, for example, does not produce any figures, but raises an import error. This PR adds support for IPython, and outputs each iteration of the interactive figure as a separate image.

Additional fixes for the Pauli error legend and missing figures.