Swedish translation

I've created a Swedish translation. There's a lot of strings in-game that are untranslated, but I assume that's just how it is for now. The ones I have seen in-game appear to be correct, including special characters like å ä and ö.

If any native speakers have comments and/or suggestions for translations, I'm listening. It's basically done except for some TODOs, but I think it's done enough for now.