[WIP] Implement Michalsky's solar position algorithm

[kandersolar]

• [x] Related to #1308
• [x] I am familiar with the contributing guidelines
• [ ] Tests added
• [ ] Updates entries in docs/sphinx/source/reference for API changes.
• [ ] Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• [ ] New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• [ ] Pull request is nearly complete and ready for detailed review.
• [ ] Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

It may be useful to compare this implementation with SOLPOS (easily available in python via SolarUtils). SOLPOS is at least partially related to Michalsky, although I'm not yet sure if their outputs should be expected to be identical.

TODO: check whether the code works in the southern hemisphere (I saw it mentioned that the "original form" of the equations does not).

[AdamRJensen]

Note, the solar position used by SOLPOS is the same as the Michalsky solar position algorithm. However, SOLPOS uses a different refraction correction algorithm than that given in the Michalsky paper.