issue #1175 redesign plugin manager

* design based on Samuel's mockup + Hannah's adaptations
* on each plugin actions shown as buttons in a single column (better compatibility with verbose languages such as German)
* description always shown (no more need of the "show details" action)
* filter based on plugin title/description (javascript, no page reload)
* hide inactive plugins if they are 8 or more
* plugins no longer shown in the admin left menu, they instead get a "settings" action if relevant. Compatible with the old trigger get_admin_plugin_menu_links but new method is to simply add a "Has Setting : true" in the main.inc.php header

admin/include/plugins.class.php

@@ -285,6 +285,7 @@ DELETE FROM '. PLUGINS_TABLE .'
           'uri'=>'',
           'description'=>'',
           'author'=>'',
+          'hasSettings'=>false,
         );
       $plg_data = file_get_contents($path.'/main.inc.php', null, null, 0, 2048);
 
@@ -316,6 +317,10 @@ DELETE FROM '. PLUGINS_TABLE .'
       {
         $plugin['author uri'] = trim($val[1]);
       }
+      if (preg_match("/Has Settings:\\s*(true|True)/", $plg_data, $val))
+      {
+        $plugin['hasSettings'] = true;
+      }
       if (!empty($plugin['uri']) and strpos($plugin['uri'] , 'extension_view.php?eid='))
       {
         list( , $extension) = explode('extension_view.php?eid=', $plugin['uri']);