implementing the faces stuff

* /admin/css/screen-details.css
	fix add a style for errors

* /admin/feed-item-detail.php
	fix typo

* /admin/js/screen-details.js
	add more of the screen editing functionality

* /lib/db.php
	add a db_free_result function

* /lib/lib.php
	allow for getting local files too in get_url_contents

* /lib/signlib.php
	fix stuff in ImageManager

* /sql/signage.sql
	add the feed type for the trombinoscope

* /lib/feed/faces.php
	add the faces plugin
implement user faces plugin