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/HTMLModule/Bdo.php

@@ -0,0 +1,44 @@
+<?php
+
+/**
+ * XHTML 1.1 Bi-directional Text Module, defines elements that
+ * declare directionality of content. Text Extension Module.
+ */
+class HTMLPurifier_HTMLModule_Bdo extends HTMLPurifier_HTMLModule
+{
+
+    /**
+     * @type string
+     */
+    public $name = 'Bdo';
+
+    /**
+     * @type array
+     */
+    public $attr_collections = array(
+        'I18N' => array('dir' => false)
+    );
+
+    /**
+     * @param HTMLPurifier_Config $config
+     */
+    public function setup($config)
+    {
+        $bdo = $this->addElement(
+            'bdo',
+            'Inline',
+            'Inline',
+            array('Core', 'Lang'),
+            array(
+                'dir' => 'Enum#ltr,rtl', // required
+                // The Abstract Module specification has the attribute
+                // inclusions wrong for bdo: bdo allows Lang
+            )
+        );
+        $bdo->attr_transform_post[] = new HTMLPurifier_AttrTransform_BdoDir();
+
+        $this->attr_collections['I18N']['dir'] = 'Enum#ltr,rtl';
+    }
+}
+
+// vim: et sw=4 sts=4