JOSS accepted version
Archival version "as accepted" to JOSS: openjournals/joss-reviews#370
Changes for issues raised in review:
- A bug, where submodules were not installing correctly using pip, has been fixed.
- The full configuration degeneracy is now preserved over a series of site substitutions.
- Examples using the pymatgen interface to auto-generate SymmetryGroup and ConfigurationSpace objects have been added to the example Jupyter notebook.