Factored out logging code in case we need to replace zlog. Zlog has a
limitation that it may be set up only by configuration file, rather
than by function calls. It also requires that users have write access
to the configuation file (as a lock file, by default), while its
alternative dedicated lock file is not flexible enough to be set up
per-user.
Merge branch 'devel' of github.com:keithj/baton into devel