Add UTF-8 BOM to votl_cheatsheet.txt

Well, my change that you just merged worked fine until I ran :helptags. It turns out that :helptags complains about mixed encodings between help files. I'm not sure why that would be, but it's easy enough to fix by adding the UTF-8 BOM to votl_cheatsheet.txt as well. There's the slight added bonus of now being able to add Unicode text to that file without issue. 

The rest of the diffs are just trailing whitespace removal.