Works decenty well assuming the title, abstract, and citation fields
are an accurate representation of the language as identified by the
language field. Handles ISO 639-1 (alpha 2) and ISO 639-3 (alpha 3)
values seamlessly.
This includes updated pipenv environment, test data, pytest tests
for both correct and incorrect ISO 639-1 and ISO 639-3 languages,
and a new command line option "-e".
