Lots of progress from yesterday's modest start of building data types for
scheduling. Last night I wrote the hairy calendar code to calculate when
next to run a scheduled event. (This is actually quite superior to `cron`,
which checks every second to see if it should run each event!) Today I
built a "Cronner" thread that handles spawning threads to handle each
scheduled event. It even notices when changes have been made to the its
schedule and stops/starts event threads appropriately.

Everything is hooked up, building, and there's a good chance it works
without too many bugs, but while I've tested all the pure code (mostly
automatically with quickcheck properties), I have not run the Cronner
thread at all. And there is some tricky stuff in there, like noticing
that the machine was asleep past when it expected to wake up, and deciding
if it should still run a scheduled event, or should wait until next time.
So tomorrow we'll see..

Today's work was sponsored by Ethan Aubin.
