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/AttrDef/HTML/Bool.php

@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * Validates a boolean attribute
+ */
+class HTMLPurifier_AttrDef_HTML_Bool extends HTMLPurifier_AttrDef
+{
+
+    protected $name;
+    public $minimized = true;
+
+    public function __construct($name = false) {$this->name = $name;}
+
+    public function validate($string, $config, $context) {
+        if (empty($string)) return false;
+        return $this->name;
+    }
+
+    /**
+     * @param $string Name of attribute
+     */
+    public function make($string) {
+        return new HTMLPurifier_AttrDef_HTML_Bool($string);
+    }
+
+}
+
+// vim: et sw=4 sts=4