First pass at adding (better) search to API docs.

Right now we mostly just have the API docs builder script
run through a documentation helper that adds a JS file to
HTML files.

For now, we’re only doing the HTML files at the root of the
documentation directory, which isn’t terribly useful, but it does
work. More to come.
Recursively add search to API docs.

The “search” that’s being added is still wrong, but the
recursion is alllll riiiiiight.
Adjust path to search.js based on file depth.

We do this by tracking a nestLevel during our recursive
descent and including it in the information describing each file.
We also wrap all that info in a FileInfo case class, which
replaces the old tuple.
Extract basic API info from docs.

Not extracting the members yet, just the item type, its name,
and its signature.