Don't do global logging configuration when running tests.

Logs may be interesting to debug test failures, but getting N copies of
every message, only after the main tests run, isn't how to do it.
Separate hamlib protocol implementation from rigctld-specific details.

This is in preparation for supporting rotctld, which uses the same protocol
structure but different specific commands.
Add support for Hamlib rotctld.

As I do not have actual rotator hardware to test against, this has only
been tested with the hamlib dummy backend. It also does not yet have
any designed UI (e.g. displaying compass points).