Issue with out of date language codes (ISO 639) used by the RDF Validator

Error: {W116} ISO-639 does not define language: 'cnr'.[Line = 71, Column 
= 75]

This is incorrect - 'cnr' is the proper language tag for Montenegrin 
(see http://id.loc.gov/vocabulary/iso639-2/cnr.html). It's a relatively 
recent change, as of December 2017, so possibly this validator has not 
been updated since the change was made. The change prior to this was in 
2012, so these codes change quite infrequently (see 
https://www.loc.gov/standards/iso639-2/php/code_changes.php).

Thanks,

Elisa Kendall