The compute thread should take an event or a save request or a
shutdown request. We now take snapshots every 120 seconds like
vere does, and take a snapshot before clean shutdown.
(Also changes the terminal driver so that it doesn't unboundedly
block shutdown.)
After looking at vty for a bit, I decided to just do a straight port
of term.c's raw output code. This gets the "~zod:dojo" in the right
position, though the other logging output screws things up a bit.
Joe told me to look at the Jaque terminal and I just did. That uses
the Lanterna Java library to handle terminal output. Joe then suggested
that I move the entire system here to curses or another similar library.
