Updated localizations from the old .xml format

Featuring Japanese, by me, new Latin translations from my friend Umune, a fr_FR that's exactly the same as fr_CA for completeness, and Serbian, Welsh, Polish, and Turkish from nine months ago. Can't figure out how to view the authors.

Missing or unsatisfactory translations are simply left out.

Also, there was a da_DK (Danish) localization, but I accidentally deleted it, so can someone good at git delve into the history and dig it up?