- admin/cat_options page added : manage options for the whole categories

tree (uploadable, commentable). status and visible will be soon added

- admin.php : $conf_link var to avoid lines longer than 79 characters

- config.upload_available configuration parameter disappear : it's simpler
  to manage with cat_options

- config.show_comments idem : new column categories.commentable, each
  categories can be commentable or not

- categories.site_id becomes a nullable column : a virtual category does
  belong to no site

- function display_select_categories has a new argument : $CSS_classes array
  to optionnaly assign a CSS class to each category in the select field

- added informations in include/config.inc.php for setting default value of :

  - categories.visible
  - categories.status
  - categories.uploadable
  - categories.commentable

- 2 new indexes images_i3(average_rate) and images_i4(hit) : optimizes best
  rated and most visited categories


git-svn-id: http://piwigo.org/svn/trunk@602 68402e56-0260-453c-a942-63ccdbb3a9ee

include/category_default.inc.php

@@ -120,7 +120,9 @@ while ($row = mysql_fetch_array($result))
       )
     );
     
-  if ($conf['show_comments'] and $user['show_nb_comments'])
+  if ($user['show_nb_comments']
+      and is_numeric($page['cat'])
+      and $page['cat_commentable'])
   {
     $query = '
 SELECT COUNT(*) AS nb_comments