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/AttrTransform/Name.php

@@ -0,0 +1,33 @@
+<?php
+
+/**
+ * Pre-transform that changes deprecated name attribute to ID if necessary
+ */
+class HTMLPurifier_AttrTransform_Name extends HTMLPurifier_AttrTransform
+{
+
+    /**
+     * @param array $attr
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array
+     */
+    public function transform($attr, $config, $context)
+    {
+        // Abort early if we're using relaxed definition of name
+        if ($config->get('HTML.Attr.Name.UseCDATA')) {
+            return $attr;
+        }
+        if (!isset($attr['name'])) {
+            return $attr;
+        }
+        $id = $this->confiscateAttr($attr, 'name');
+        if (isset($attr['id'])) {
+            return $attr;
+        }
+        $attr['id'] = $id;
+        return $attr;
+    }
+}
+
+// vim: et sw=4 sts=4