Generated API documentation

[MostAwesomeDude]

We should be able to take modules and send them to API docs somehow. By case analysis on each of the modules we support:

• Standard .mt source code is sent to API docs, as a base case
• .mt.md literate source code is sent to Pandoc so that the literate sections can be nicely laid out, and the untangled source code is turned into API docs, and then those are concatenated
• .asdl Zephyr ASDL type declaration is sent to ML/Haskell-ish datatype declaration plus basic API docs and how-to-ASDL blurb

On top of all of this, when we send an entire directory of modules to docs, we should generate a table of contents. We also should allow for some sort of custom documentation hook:

• Parsers should be able to export railroad diagrams somehow
• Interfaces should be able to export their signatures
• Auditors should be able to declare their behaviors somewhat?
• Controllers should be able to declare their control words