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/AttrTransform/EnumToCSS.php

@@ -0,0 +1,58 @@
+<?php
+
+/**
+ * Generic pre-transform that converts an attribute with a fixed number of
+ * values (enumerated) to CSS.
+ */
+class HTMLPurifier_AttrTransform_EnumToCSS extends HTMLPurifier_AttrTransform {
+
+    /**
+     * Name of attribute to transform from
+     */
+    protected $attr;
+
+    /**
+     * Lookup array of attribute values to CSS
+     */
+    protected $enumToCSS = array();
+
+    /**
+     * Case sensitivity of the matching
+     * @warning Currently can only be guaranteed to work with ASCII
+     *          values.
+     */
+    protected $caseSensitive = false;
+
+    /**
+     * @param $attr String attribute name to transform from
+     * @param $enumToCSS Lookup array of attribute values to CSS
+     * @param $case_sensitive Boolean case sensitivity indicator, default false
+     */
+    public function __construct($attr, $enum_to_css, $case_sensitive = false) {
+        $this->attr = $attr;
+        $this->enumToCSS = $enum_to_css;
+        $this->caseSensitive = (bool) $case_sensitive;
+    }
+
+    public function transform($attr, $config, $context) {
+
+        if (!isset($attr[$this->attr])) return $attr;
+
+        $value = trim($attr[$this->attr]);
+        unset($attr[$this->attr]);
+
+        if (!$this->caseSensitive) $value = strtolower($value);
+
+        if (!isset($this->enumToCSS[$value])) {
+            return $attr;
+        }
+
+        $this->prependCSS($attr, $this->enumToCSS[$value]);
+
+        return $attr;
+
+    }
+
+}
+
+// vim: et sw=4 sts=4