Update MarkdownHandler to duplicate file to `_tmp`, escape <?php and @
Update MarkdownHandler to duplicate file to `_tmp`, escape <?php and @

tightenco/jigsaw,adamwathan/jigsaw,adamwathan/jigsaw,tightenco/jigsaw,quickliketurtle/jigsaw,tightenco/jigsaw,quickliketurtle/jigsaw,quickliketurtle/jigsaw