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/Hypertext.php

@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * XHTML 1.1 Hypertext Module, defines hypertext links. Core Module.
+ */
+class HTMLPurifier_HTMLModule_Hypertext extends HTMLPurifier_HTMLModule
+{
+
+    /**
+     * @type string
+     */
+    public $name = 'Hypertext';
+
+    /**
+     * @param HTMLPurifier_Config $config
+     */
+    public function setup($config)
+    {
+        $a = $this->addElement(
+            'a',
+            'Inline',
+            'Inline',
+            'Common',
+            array(
+                // 'accesskey' => 'Character',
+                // 'charset' => 'Charset',
+                'href' => 'URI',
+                // 'hreflang' => 'LanguageCode',
+                'rel' => new HTMLPurifier_AttrDef_HTML_LinkTypes('rel'),
+                'rev' => new HTMLPurifier_AttrDef_HTML_LinkTypes('rev'),
+                // 'tabindex' => 'Number',
+                // 'type' => 'ContentType',
+            )
+        );
+        $a->formatting = true;
+        $a->excludes = array('a' => true);
+    }
+}
+
+// vim: et sw=4 sts=4