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/PropertyList.php

@@ -0,0 +1,122 @@
+<?php
+
+/**
+ * Generic property list implementation
+ */
+class HTMLPurifier_PropertyList
+{
+    /**
+     * Internal data-structure for properties.
+     * @type array
+     */
+    protected $data = array();
+
+    /**
+     * Parent plist.
+     * @type HTMLPurifier_PropertyList
+     */
+    protected $parent;
+
+    /**
+     * Cache.
+     * @type array
+     */
+    protected $cache;
+
+    /**
+     * @param HTMLPurifier_PropertyList $parent Parent plist
+     */
+    public function __construct($parent = null)
+    {
+        $this->parent = $parent;
+    }
+
+    /**
+     * Recursively retrieves the value for a key
+     * @param string $name
+     * @throws HTMLPurifier_Exception
+     */
+    public function get($name)
+    {
+        if ($this->has($name)) {
+            return $this->data[$name];
+        }
+        // possible performance bottleneck, convert to iterative if necessary
+        if ($this->parent) {
+            return $this->parent->get($name);
+        }
+        throw new HTMLPurifier_Exception("Key '$name' not found");
+    }
+
+    /**
+     * Sets the value of a key, for this plist
+     * @param string $name
+     * @param mixed $value
+     */
+    public function set($name, $value)
+    {
+        $this->data[$name] = $value;
+    }
+
+    /**
+     * Returns true if a given key exists
+     * @param string $name
+     * @return bool
+     */
+    public function has($name)
+    {
+        return array_key_exists($name, $this->data);
+    }
+
+    /**
+     * Resets a value to the value of it's parent, usually the default. If
+     * no value is specified, the entire plist is reset.
+     * @param string $name
+     */
+    public function reset($name = null)
+    {
+        if ($name == null) {
+            $this->data = array();
+        } else {
+            unset($this->data[$name]);
+        }
+    }
+
+    /**
+     * Squashes this property list and all of its property lists into a single
+     * array, and returns the array. This value is cached by default.
+     * @param bool $force If true, ignores the cache and regenerates the array.
+     * @return array
+     */
+    public function squash($force = false)
+    {
+        if ($this->cache !== null && !$force) {
+            return $this->cache;
+        }
+        if ($this->parent) {
+            return $this->cache = array_merge($this->parent->squash($force), $this->data);
+        } else {
+            return $this->cache = $this->data;
+        }
+    }
+
+    /**
+     * Returns the parent plist.
+     * @return HTMLPurifier_PropertyList
+     */
+    public function getParent()
+    {
+        return $this->parent;
+    }
+
+    /**
+     * Sets the parent plist.
+     * @param HTMLPurifier_PropertyList $plist Parent plist
+     */
+    public function setParent($plist)
+    {
+        $this->parent = $plist;
+    }
+}
+
+// vim: et sw=4 sts=4