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/RemoveSpansWithoutAttributes.php

@@ -0,0 +1,84 @@
+<?php
+
+/**
+ * Injector that removes spans with no attributes
+ */
+class HTMLPurifier_Injector_RemoveSpansWithoutAttributes extends HTMLPurifier_Injector
+{
+    /**
+     * @type string
+     */
+    public $name = 'RemoveSpansWithoutAttributes';
+
+    /**
+     * @type array
+     */
+    public $needed = array('span');
+
+    /**
+     * @type HTMLPurifier_AttrValidator
+     */
+    private $attrValidator;
+
+    /**
+     * Used by AttrValidator.
+     * @type HTMLPurifier_Config
+     */
+    private $config;
+
+    /**
+     * @type HTMLPurifier_Context
+     */
+    private $context;
+
+    public function prepare($config, $context)
+    {
+        $this->attrValidator = new HTMLPurifier_AttrValidator();
+        $this->config = $config;
+        $this->context = $context;
+        return parent::prepare($config, $context);
+    }
+
+    /**
+     * @param HTMLPurifier_Token $token
+     */
+    public function handleElement(&$token)
+    {
+        if ($token->name !== 'span' || !$token instanceof HTMLPurifier_Token_Start) {
+            return;
+        }
+
+        // We need to validate the attributes now since this doesn't normally
+        // happen until after MakeWellFormed. If all the attributes are removed
+        // the span needs to be removed too.
+        $this->attrValidator->validateToken($token, $this->config, $this->context);
+        $token->armor['ValidateAttributes'] = true;
+
+        if (!empty($token->attr)) {
+            return;
+        }
+
+        $nesting = 0;
+        while ($this->forwardUntilEndToken($i, $current, $nesting)) {
+        }
+
+        if ($current instanceof HTMLPurifier_Token_End && $current->name === 'span') {
+            // Mark closing span tag for deletion
+            $current->markForDeletion = true;
+            // Delete open span tag
+            $token = false;
+        }
+    }
+
+    /**
+     * @param HTMLPurifier_Token $token
+     */
+    public function handleEnd(&$token)
+    {
+        if ($token->markForDeletion) {
+            $token = false;
+        }
+    }
+}
+
+// vim: et sw=4 sts=4