Stem::Console Design Notes

The Stem::Console is a class Cell which provides a simple command line
interface to a Stem Hub. It parses lines typed into stdin and creates
and dispatches command type Stem Messages from them. It also can accept
and print response messages sent back by the command method in the
addressed Cell.

This class Cell is registered under its class name and with the
nicknames console, cons, and tty.  It takes no configure arguments and
it just creates an Stem::AsyncIO object to handle the console I/O.

When you see the Stem> prompt, you can enter 'help' to see how to enter
messages and commands.