HTMLRenderer: Strip newline characters
HTMLRenderer: Strip newline characters

Don't let HTMLRenderer pass newline characters as they are evaluated as
non-printable later on.

newsboat/newsboat,x4121/newsbeuter,der-lyse/newsboat,der-lyse/newsboat,der-lyse/newsboat,x4121/newsbeuter,der-lyse/newsboat,newsboat/newsboat,x4121/newsbeuter,der-lyse/newsboat,newsboat/newsboat,x4121/newsbeuter,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat