add piwik installation

www/analytics/core/Plugin/API.php

@@ -0,0 +1,45 @@
+<?php
+/**
+ * Piwik - Open source web analytics
+ *
+ * @link http://piwik.org
+ * @license http://www.gnu.org/licenses/gpl-3.0.html GPL v3 or later
+ *
+ */
+
+namespace Piwik\Plugin;
+
+use Piwik\Singleton;
+
+/**
+ * The base class of all API singletons.
+ * 
+ * Plugins that want to expose functionality through the Reporting API should create a class
+ * that extends this one. Every public method in that class that is not annotated with **@ignore**
+ * will be callable through Piwik's Web API.
+ * 
+ * _Note: If your plugin calculates and stores reports, they should be made available through the API._
+ * 
+ * ### Examples
+ * 
+ * **Defining an API for a plugin**
+ * 
+ *     class API extends \Piwik\Plugin\API
+ *     {
+ *         public function myMethod($idSite, $period, $date, $segment = false)
+ *         {
+ *             $dataTable = // ... get some data ...
+ *             return $dataTable;
+ *         }
+ *     }
+ * 
+ * **Linking to an API method**
+ * 
+ *     <a href="?module=API&method=MyPlugin.myMethod&idSite=1&period=day&date=2013-10-23">Link</a>
+ * 
+ * @api
+ */
+abstract class API extends Singleton
+{
+
+}