Add website to client repository

Closes #1567

The main reason I'm not simply merging Annika's PR is because this
way makes it clearer that I'm taking responsibility for all this
code, that it's mostly code I wrote, and also because it makes it
easier to ensure that none of the files have been changed.

(Not that I don't personally trust Annika, but I have something
resembling an obligation to users not to expose them to risks based
on personal trust.)

website/lib/htmlpurifier/HTMLPurifier/HTMLModule/StyleAttribute.php

@@ -0,0 +1,24 @@
+<?php
+
+/**
+ * XHTML 1.1 Edit Module, defines editing-related elements. Text Extension
+ * Module.
+ */
+class HTMLPurifier_HTMLModule_StyleAttribute extends HTMLPurifier_HTMLModule
+{
+
+    public $name = 'StyleAttribute';
+    public $attr_collections = array(
+        // The inclusion routine differs from the Abstract Modules but
+        // is in line with the DTD and XML Schemas.
+        'Style' => array('style' => false), // see constructor
+        'Core' => array(0 => array('Style'))
+    );
+
+    public function setup($config) {
+        $this->attr_collections['Style']['style'] = new HTMLPurifier_AttrDef_CSS();
+    }
+
+}
+
+// vim: et sw=4 sts=4