Node-by-node documentation for all modules in the library

[markalanboyd]

I intend to create node-by-node documentation, akin to commenting every line of code, for every module in the library.

The purpose would be to make the modules as discoverable and readable as possible for people who would like to learn how they work.

The benefit of this would be that people could learn how things are made and take the concepts they learn and make new things. Conversely, someone might be able to read what is happening in a patch and realize from a text description that there is perhaps a more efficient or elegant way to do the same thing and suggest an enhancement or fix.