Single-digit Roman numeral suffixes parsed as last initial

[hkcountryman]

This may be related to issue 11, NPM version not up to date.

When testing the names "Nicholas Runolfsdottir I" and "Nicholas Runolfsdottir V", I and V were output as last initials, respectively. II, III, and IV all work as intended (Runolfsdottir is output as last name).

I see V is on the list of suffixes in this repository, but have not had a chance to check if the latest version available here has the same issue. Regardless, the version downloaded from NPM does.