Revert "remove htmlpurifier"

This reverts commit c21a462d52.

lib/htmlpurifier/library/HTMLPurifier/AttrTransform/ScriptRequired.php

@@ -0,0 +1,16 @@
+<?php
+
+/**
+ * Implements required attribute stipulation for <script>
+ */
+class HTMLPurifier_AttrTransform_ScriptRequired extends HTMLPurifier_AttrTransform
+{
+    public function transform($attr, $config, $context) {
+        if (!isset($attr['type'])) {
+            $attr['type'] = 'text/javascript';
+        }
+        return $attr;
+    }
+}
+
+// vim: et sw=4 sts=4