- Initial work for #642. CLI commands will configure this log handler so
that they write warnings and errors to stderr, and only proper output
will go to stdout.
- Facilitates #507. The `--debug` option can set the logging level
appropriately, and CLI commands can just use `log.debug()`.
## Type of Change
- [ ] Bug fix
- [x] New feature
- [ ] Breaking change
- [ ] Documentation update