Developer's Guide

[yoelcortes]

Topics of discussion:

0. A note on the scope of the "Chemicals" project.
1. Lazy loading (keeping load speed fast).
2. Add assertion tests for new data sets, functions, and exceptions.
3. Add documentation using NumpyDoc style. Also add examples that run with doctests.
4. Use pytests and pytest --doctest-modules?
5. How to make github contributions.