A field trial for the automatically named logger.

Can be enabled with -Dorg.slf4j.LoggerFactory.autoNamedLoggerFieldTrial=true.

Prints an error (and stacktrace) to stderr when a mismatch between custom and automatic logger names is detected.
We will need a note stating that people who use the trial should use the same class as is declaring the Logger.

Also, perhaps a different flag that will merely WARN instead of throwing an exception. If just one of my classes uses a different class than itself to get a Logger, the whole system goes down. I would be inclined to stop testing after that.