Mark notes to translators as extracted comments

The notes were incorrectly marked as being filename references instead of extracted comments. For example, the note ‘For speech bubbles of the narrator` was marked as being references to source files named ‘For’, ‘speech’, ‘bubbles’, ‘of’, ‘the’ and ‘narrator’.

(In the PO editor Lokalize, they were being turned into newline-separated clickable links, and in Poedit, they were simply hidden …)