Revert "remove htmlpurifier"

This reverts commit c21a462d52.

lib/htmlpurifier/library/HTMLPurifier/URIScheme/news.php

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * Validates news (Usenet) as defined by generic RFC 1738
+ */
+class HTMLPurifier_URIScheme_news extends HTMLPurifier_URIScheme {
+
+    public $browsable = false;
+    public $may_omit_host = true;
+
+    public function doValidate(&$uri, $config, $context) {
+        $uri->userinfo = null;
+        $uri->host     = null;
+        $uri->port     = null;
+        $uri->query    = null;
+        // typecode check needed on path
+        return true;
+    }
+
+}
+
+// vim: et sw=4 sts=4