Build infrastructure to handle language tags in MODS xml. This is a breaking binary change, so bump the major version number.
Properly handle the 'date' field in xml2biblatex to output (when possible) ISO 8601 dates, otherwise default to 'year' and 'month' tags. Propagate better handling of month code to the other converters so that months are internally stored as number strings, e.g. '01' instead of 'January' or 'Jan'. Reported by sgarfield.
Handle shortjournal/shortbooktitle/shortseries in biblatex input.
Handle 'nonSort' title tag in MODS. Reported by matt.
Cleanups to MODS output.
Handle MARC country codes properly.
Convert code to use common page handling routines. Fixes nbib2xml error reported by Nina Birych.
Add additional input types to nbib2xml. Reported by Nina Birych.