These are the translations for Laravel's Validation component. They are in their own top-level namespace. Unlike the rest of Flarum's translations, the variables are marked by a :colon prefix rather than {curlies}.
Flarum is now powered by Symfony's Translation component, which has a more powerful pluralization system. The rules for all locales are included in core so they no longer need to be included per-language pack. See http://symfony.com/doc/current/components/translation/usage.html#pluralization to learn about the format.
closes#550