Uravu

Changes

- Support for the calculation of the posterior predictive distribution for a given abscissa set.
- Catch up to the latest version of `dynesty`

Changes

- Addition some `__ufunc__` options and fixing `Distribution` `__repr__()`.

Changes:
- Add some `to_dict` and `from_dict` methods.

Changes:
- Pinned version of `dynesty`.

Changes:
- Addition of the `flatchain` property for the `Relationship` class.