Replace existing autoloader with Composer-supplied

- Move Friendica namespace to `src`
- Move required `ezyang/htmlpurifier` to vendor
- Remove existing static autoloader
- Change boot.php reference to the autoloader

vendor/ezyang/htmlpurifier/library/HTMLPurifier/ConfigSchema/Interchange/Id.php

@@ -0,0 +1,58 @@
+<?php
+
+/**
+ * Represents a directive ID in the interchange format.
+ */
+class HTMLPurifier_ConfigSchema_Interchange_Id
+{
+
+    /**
+     * @type string
+     */
+    public $key;
+
+    /**
+     * @param string $key
+     */
+    public function __construct($key)
+    {
+        $this->key = $key;
+    }
+
+    /**
+     * @return string
+     * @warning This is NOT magic, to ensure that people don't abuse SPL and
+     *          cause problems for PHP 5.0 support.
+     */
+    public function toString()
+    {
+        return $this->key;
+    }
+
+    /**
+     * @return string
+     */
+    public function getRootNamespace()
+    {
+        return substr($this->key, 0, strpos($this->key, "."));
+    }
+
+    /**
+     * @return string
+     */
+    public function getDirective()
+    {
+        return substr($this->key, strpos($this->key, ".") + 1);
+    }
+
+    /**
+     * @param string $id
+     * @return HTMLPurifier_ConfigSchema_Interchange_Id
+     */
+    public static function make($id)
+    {
+        return new HTMLPurifier_ConfigSchema_Interchange_Id($id);
+    }
+}
+
+// vim: et sw=4 sts=4