* Added `sirad validate` command (4).
* Consistently use logging instead of print, and set the logging module name with logging.getLogger(name) (6).
* Added threshold on date parsing debug statements.
* Additional address prefixes for censuscoding (mailing, employer1, employer2, employer3).
* Added `--verbose` option.
* Remove quotes from CSV header values in `sirad validate`.
* Use `low_memory=False` in Pandas `read_csv()` calls in `research.py` to address Pandas warnings.
* Additional mappings for non-ASCII characters in `readers.py`.