A little whitespace now & then / is relished by the wisest of men.
The worker is now restartable.

That is, you can call stop() and then start() on it without needing to
create a new one. You'll still need to re-watch any tubes you were
watching. (Going to rework that, at which point this client will be far
divorced from the original project.)

Implemented more worker tests. Client test coverage is now at 91% and
worker coverage at 92%.