Revert "remove htmlpurifier"

This reverts commit c21a462d52.

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

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * Dummy AttrDef that mimics another AttrDef, BUT it generates clones
+ * with make.
+ */
+class HTMLPurifier_AttrDef_Clone extends HTMLPurifier_AttrDef
+{
+    /**
+     * What we're cloning
+     */
+    protected $clone;
+
+    public function __construct($clone) {
+        $this->clone = $clone;
+    }
+
+    public function validate($v, $config, $context) {
+        return $this->clone->validate($v, $config, $context);
+    }
+
+    public function make($string) {
+        return clone $this->clone;
+    }
+
+}
+
+// vim: et sw=4 sts=4