Metacast

Expanded Latin Hypercube sampling beyond uniform distribution see:
* https://github.com/m-d-grunnill/MetaCast/issues/8
* https://github.com/m-d-grunnill/MetaCast/pull/9

JOSS review

Release deals with edits/corrections suggested by [JOSS](https://joss.theoj.org/) review process, see issues:
* [JOSS Review - Recommended Edits for Paper.md](https://github.com/m-d-grunnill/MetaCast/issues/3).
* [Cannot run test cases: ModuleNotFoundError](https://github.com/m-d-grunnill/MetaCast/issues/4)
* [Possible typos in example notebook and MetaCast package](https://github.com/m-d-grunnill/MetaCast/issues/5)
* [Latin Hypercube sampling only supports uniform distributions](https://github.com/m-d-grunnill/MetaCast/issues/6)

Release for JOSS submission.