ISO639-2 Data Types.
Source data from the ISO639-2 maintainers at the Library of Congress:
http://www.loc.gov/standards/iso639-2/ISO-639-2_utf-8.txt
More grandular data is encoded in the ISO639-3 spec:
http://www-01.sil.org/iso639-3/iso-639-3_20130520.tab
However I'm currently using -2 since it covers my current needs. If there is intrest, we can easily extend this package to cover -3 also.