[DUTCH] Translated all of the new strings, a lot of spelling & grammar fixes, more uniformity

Translated all of the new strings from the latest update, fixed a lot of spelling and grammar mistakes and added more uniformity (so the same terms are used throughout the whole website).

(In case anyone is interested, for tips: 1AoFWdTDTVnMypWKM12ykmPKN4a2ks1rLS - Thanks!)