Added HTMLPurifier (http://htmlpurifier.org/) Version 3.3.0

- can be used via html class like: 

        $clean_html = html::purify($html);

- using it now in eTemplate to remove malicious code from html:
  a) when displaying "formatted text"
  b) when "formatted text" get's input by the user

phpgwapi/inc/htmlpurifier/library/HTMLPurifier/HTMLModule/Tidy/Strict.php

@@ -0,0 +1,21 @@
+<?php
+
+class HTMLPurifier_HTMLModule_Tidy_Strict extends HTMLPurifier_HTMLModule_Tidy_XHTMLAndHTML4
+{
+    public $name = 'Tidy_Strict';
+    public $defaultLevel = 'light';
+
+    public function makeFixes() {
+        $r = parent::makeFixes();
+        $r['blockquote#content_model_type'] = 'strictblockquote';
+        return $r;
+    }
+
+    public $defines_child_def = true;
+    public function getChildDef($def) {
+        if ($def->content_model_type != 'strictblockquote') return parent::getChildDef($def);
+        return new HTMLPurifier_ChildDef_StrictBlockquote($def->content_model);
+    }
+}
+
+// vim: et sw=4 sts=4