Use UTF8 encoding instead of ISO-8859-1

@stefjoosten & @Ferlon: If you're working on these files and get a merge conflict, you can simply take your version and convert it to UTF8 before committing. It is unclear why these files cause problems on my Mac and Windows installations, but not on yours. For the future, maybe it is possible to set the default encoding for new files to UTF8 in your text editors?