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/Node/Element.php

@@ -0,0 +1,59 @@
+<?php
+
+/**
+ * Concrete element node class.
+ */
+class HTMLPurifier_Node_Element extends HTMLPurifier_Node
+{
+    /**
+     * The lower-case name of the tag, like 'a', 'b' or 'blockquote'.
+     *
+     * @note Strictly speaking, XML tags are case sensitive, so we shouldn't
+     * be lower-casing them, but these tokens cater to HTML tags, which are
+     * insensitive.
+     * @type string
+     */
+    public $name;
+
+    /**
+     * Associative array of the node's attributes.
+     * @type array
+     */
+    public $attr = array();
+
+    /**
+     * List of child elements.
+     * @type array
+     */
+    public $children = array();
+
+    /**
+     * Does this use the <a></a> form or the </a> form, i.e.
+     * is it a pair of start/end tokens or an empty token.
+     * @bool
+     */
+    public $empty = false;
+
+    public $endCol = null, $endLine = null, $endArmor = array();
+
+    public function __construct($name, $attr = array(), $line = null, $col = null, $armor = array()) {
+        $this->name = $name;
+        $this->attr = $attr;
+        $this->line = $line;
+        $this->col = $col;
+        $this->armor = $armor;
+    }
+
+    public function toTokenPair() {
+        // XXX inefficiency here, normalization is not necessary
+        if ($this->empty) {
+            return array(new HTMLPurifier_Token_Empty($this->name, $this->attr, $this->line, $this->col, $this->armor), null);
+        } else {
+            $start = new HTMLPurifier_Token_Start($this->name, $this->attr, $this->line, $this->col, $this->armor);
+            $end = new HTMLPurifier_Token_End($this->name, array(), $this->endLine, $this->endCol, $this->endArmor);
+            //$end->start = $start;
+            return array($start, $end);
+        }
+    }
+}
+