More fixes, translated remaining string

As indicated by AaronVanGeffen.

I quickly walked trough the entire file, fixing some translations, including a few for consistency, and a few to prevent overflowing. Also translated what _seemed_ like the only remaining untranslated string! (Not counting strings that are currently untranslatable.) In other words, it means dutch.txt is as complete as it can currently get.

@AaronVanGeffen: could you take a look as well and tell if you can find any errors?
@IcyPalm Yes yes, I'm not the only one who thought that way. In the Dutch language it indeedly means there is something missing, mostly you have to "finish the sentence in your own mind". So, maybe we could change this to "Neem [person] aan"? It fits and looks much nicer.