-That would run the text through the pl htmlizer, from the syntax hightligh
-plugin. OTOH, if "rst" were given, it would run the text through the rst
-htmlizer. So, more generic, allows mixing different types of markup on one
-page, as well as syntax highlighting. Does require specifying the type of
-format, instead of allowing it to be guessed (which some syntax highlighters
-can do). (This directive is now implemented..)