License the code as MIT (keep the rest CC-BY)

[moorepants]

It is more appropriate to use a OSI aprpoved opensource license for the code in the text so that it can be more easily copied into other programs. CC-BY has some clauses that may not be that favorable for software reuse: https://opensource.stackexchange.com/questions/9242/why-does-creative-commons-recommend-not-using-cc-by-licenses-for-software. I think I can license all the code as MIT except the Jupyter/Python and Vector chapters because I took a lot of that from the PyDy Human Standing Tutorial. So I would need to figure out what has to be CC-BY in the current text.