Until now i always had the translations be empty strings if some columns
did not have the full translation, but this is going too far on the
non-NULL policy: surely they have a translations, but we do not know it
yet; this is the exact type of situations NULL values are for.
Besides the philosophical distinction, having empty strings instead of
NULLs is less practical, because i no longer can user coalesce() to
retrieve the default language text in case the translation for that
particular field is not available, even if the row for a locale exists.
In time i will change all _i18n relations, but for now only these from
campsite follow the “new policy”.