Logging to a vacuum

We stopped using println in favour of the log crate, and that’s great in theory. The issue is that we actually don’t log anything now because we haven’t configured an implementation to use. The log crate documentation says:

If no logging implementation is selected, the facade falls back to a "noop" implementation that ignores all log messages.

There is a long list of implementations to choose from, at a first quick glance syslog seems to be one we ought to use, but it’s worth investigating other options.

set_logger and set_max_level need to be called.