[RFC] Update Swedish (sv) translation

Updated all fuzzy and missing translations, plus some additional style changes.

Here I have changed the translation to use the English words when referring to the vimscript datatypes: Dictionary, Float etc, just like the German translation. (I think some of the existing translations, Nummer -> Siffra for example, is not that good anyway)

I'm not sure I like "framhävning" as translation of highlighting, but I cannot figure a better option (that is an obvious translation of highlighting). The same with "skiljeläge" for diff mode, maybe it just should be "diff-läge"?