Dutch translation improvements

DO NOT MERGE YET! STILL WIP!

I'm looking at the Dutch translations and see if I can fix or/and improve some translations. I will look further today at this, so till I say it, do not merge it yet. In the mean time the other Dutch translators (for example @Gymnasiast ) can look at the changes I have made so far and can descide if it's a good change or not. Just want to let you know I'm working on it, so we don't do dubble work :) 
@IntelOrca Are the strings in the language files already used, or do we still see the strings in the executable? We wonder if the "award strings" are also used in the news items on the bottom of the game screen, as well as the awards window. We're talking about the strings starting from `STR_2814`, a.k.a `STR_AWARD_MOST_UNTIDY`.