update Piwik to version 2.16 (fixes #91)

www/analytics/core/Singleton.php

@@ -1,6 +1,6 @@
 <?php
 /**
- * Piwik - Open source web analytics
+ * Piwik - free/libre analytics platform
  *
  * @link http://piwik.org
  * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
@@ -11,7 +11,7 @@ namespace Piwik;
 
 /**
  * The singleton base class restricts the instantiation of derived classes to one object only.
- * 
+ *
  * All plugin APIs are singletons and thus extend this class.
  *
  * @api
@@ -20,17 +20,22 @@ class Singleton
 {
     protected static $instances;
 
-    protected function __construct() { }
+    protected function __construct()
+    {
+    }
 
-    final private function __clone() { }
+    final private function __clone()
+    {
+    }
 
     /**
      * Returns the singleton instance for the derived class. If the singleton instance
      * has not been created, this method will create it.
      *
-     * @return Singleton
+     * @return static
      */
-    public static function getInstance() {
+    public static function getInstance()
+    {
         $class = get_called_class();
 
         if (!isset(self::$instances[$class])) {
@@ -58,4 +63,12 @@ class Singleton
         $class = get_called_class();
         self::$instances[$class] = $instance;
     }
+
+    /**
+     * @ignore
+     */
+    public static function clearAll()
+    {
+        self::$instances = array();
+    }
 }