Add some broken tests and sketches for transactions that lead me to think about transactions, ends, and errors, more deeply.
Add a not-yet-ready cells.html example.
Add pretext dependency for the upcoming documentation.
Add skeletal documentation. docs/mk to generate it into docs/index.html.
More documentation, rename .md -> .pre.
Don't really know what to do with this.
Disable the .set()-.end() test for now, let's do some other internal changes and let the thoughts on that subject cook for a while.
README is a .pre, too, actually. Sorry github, let's think about something.