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/Injector/PurifierLinkify.php

@@ -0,0 +1,71 @@
+<?php
+
+/**
+ * Injector that converts configuration directive syntax %Namespace.Directive
+ * to links
+ */
+class HTMLPurifier_Injector_PurifierLinkify extends HTMLPurifier_Injector
+{
+    /**
+     * @type string
+     */
+    public $name = 'PurifierLinkify';
+
+    /**
+     * @type string
+     */
+    public $docURL;
+
+    /**
+     * @type array
+     */
+    public $needed = array('a' => array('href'));
+
+    /**
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return string
+     */
+    public function prepare($config, $context)
+    {
+        $this->docURL = $config->get('AutoFormat.PurifierLinkify.DocURL');
+        return parent::prepare($config, $context);
+    }
+
+    /**
+     * @param HTMLPurifier_Token $token
+     */
+    public function handleText(&$token)
+    {
+        if (!$this->allowsElement('a')) {
+            return;
+        }
+        if (strpos($token->data, '%') === false) {
+            return;
+        }
+
+        $bits = preg_split('#%([a-z0-9]+\.[a-z0-9]+)#Si', $token->data, -1, PREG_SPLIT_DELIM_CAPTURE);
+        $token = array();
+
+        // $i = index
+        // $c = count
+        // $l = is link
+        for ($i = 0, $c = count($bits), $l = false; $i < $c; $i++, $l = !$l) {
+            if (!$l) {
+                if ($bits[$i] === '') {
+                    continue;
+                }
+                $token[] = new HTMLPurifier_Token_Text($bits[$i]);
+            } else {
+                $token[] = new HTMLPurifier_Token_Start(
+                    'a',
+                    array('href' => str_replace('%s', $bits[$i], $this->docURL))
+                );
+                $token[] = new HTMLPurifier_Token_Text('%' . $bits[$i]);
+                $token[] = new HTMLPurifier_Token_End('a');
+            }
+        }
+    }
+}
+
+// vim: et sw=4 sts=4