Persim

- Fix bug in Wasserstein and bottleneck distance.

- Include Wasserstein distance.

- Add license and README to distributed packages

- Include modified Gromov--Hausdorff distance

- Include diagram plotting
- revamped documentation

- Implementation of sliced wasserstein (thanks Alice Patania)
- Implementation of heat kernel and bottleneck distance (thanks Chris Tralie)
- Expansion of documentation