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/ChildDef/Required.php

@@ -0,0 +1,118 @@
+<?php
+
+/**
+ * Definition that allows a set of elements, but disallows empty children.
+ */
+class HTMLPurifier_ChildDef_Required extends HTMLPurifier_ChildDef
+{
+    /**
+     * Lookup table of allowed elements.
+     * @type array
+     */
+    public $elements = array();
+
+    /**
+     * Whether or not the last passed node was all whitespace.
+     * @type bool
+     */
+    protected $whitespace = false;
+
+    /**
+     * @param array|string $elements List of allowed element names (lowercase).
+     */
+    public function __construct($elements)
+    {
+        if (is_string($elements)) {
+            $elements = str_replace(' ', '', $elements);
+            $elements = explode('|', $elements);
+        }
+        $keys = array_keys($elements);
+        if ($keys == array_keys($keys)) {
+            $elements = array_flip($elements);
+            foreach ($elements as $i => $x) {
+                $elements[$i] = true;
+                if (empty($i)) {
+                    unset($elements[$i]);
+                } // remove blank
+            }
+        }
+        $this->elements = $elements;
+    }
+
+    /**
+     * @type bool
+     */
+    public $allow_empty = false;
+
+    /**
+     * @type string
+     */
+    public $type = 'required';
+
+    /**
+     * @param array $children
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array
+     */
+    public function validateChildren($children, $config, $context)
+    {
+        // Flag for subclasses
+        $this->whitespace = false;
+
+        // if there are no tokens, delete parent node
+        if (empty($children)) {
+            return false;
+        }
+
+        // the new set of children
+        $result = array();
+
+        // whether or not parsed character data is allowed
+        // this controls whether or not we silently drop a tag
+        // or generate escaped HTML from it
+        $pcdata_allowed = isset($this->elements['#PCDATA']);
+
+        // a little sanity check to make sure it's not ALL whitespace
+        $all_whitespace = true;
+
+        $stack = array_reverse($children);
+        while (!empty($stack)) {
+            $node = array_pop($stack);
+            if (!empty($node->is_whitespace)) {
+                $result[] = $node;
+                continue;
+            }
+            $all_whitespace = false; // phew, we're not talking about whitespace
+
+            if (!isset($this->elements[$node->name])) {
+                // special case text
+                // XXX One of these ought to be redundant or something
+                if ($pcdata_allowed && $node instanceof HTMLPurifier_Node_Text) {
+                    $result[] = $node;
+                    continue;
+                }
+                // spill the child contents in
+                // ToDo: Make configurable
+                if ($node instanceof HTMLPurifier_Node_Element) {
+                    for ($i = count($node->children) - 1; $i >= 0; $i--) {
+                        $stack[] = $node->children[$i];
+                    }
+                    continue;
+                }
+                continue;
+            }
+            $result[] = $node;
+        }
+        if (empty($result)) {
+            return false;
+        }
+        if ($all_whitespace) {
+            $this->whitespace = true;
+            return false;
+        }
+        return $result;
+    }
+}
+
+// vim: et sw=4 sts=4