I've created a text filter to convert URLs to Pens from codepen.io to the embedded view.
simply paste a URL to a pen (the first line below):
and it will embed:
URLs that are linked are escaped, so make sure if you have urltolink enabled that CodePen comes first:
only one setting is provided, which is to adjust the height of the embedded Pen. Can't add more settings because CodePen doesn't have an API. Here it is at 500 (default 268)