Revert "remove htmlpurifier"

This reverts commit c21a462d52.

lib/htmlpurifier/library/HTMLPurifier/AttrDef/Text.php

@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * Validates arbitrary text according to the HTML spec.
+ */
+class HTMLPurifier_AttrDef_Text extends HTMLPurifier_AttrDef
+{
+
+    public function validate($string, $config, $context) {
+        return $this->parseCDATA($string);
+    }
+
+}
+
+// vim: et sw=4 sts=4