Process main page (linklist) through Slim controller

Including a bunch of improvements on the container,
and helper used across new controllers.

application/render/PageBuilder.php

@@ -69,6 +69,15 @@ class PageBuilder
         $this->isLoggedIn = $isLoggedIn;
     }
 
+    /**
+     * Reset current state of template rendering.
+     * Mostly useful for error handling. We remove everything, and display the error template.
+     */
+    public function reset(): void
+    {
+        $this->tpl = false;
+    }
+
     /**
      * Initialize all default tpl tags.
      */

application/render/TemplatePage.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Shaarli\Render;
+
+interface TemplatePage
+{
+    public const ERROR_404 = '404';
+    public const ADDLINK = 'addlink';
+    public const CHANGE_PASSWORD = 'changepassword';
+    public const CHANGE_TAG = 'changetag';
+    public const CONFIGURE = 'configure';
+    public const DAILY = 'daily';
+    public const DAILY_RSS = 'dailyrss';
+    public const EDIT_LINK = 'editlink';
+    public const ERROR = 'error';
+    public const EXPORT = 'export';
+    public const NETSCAPE_EXPORT_BOOKMARKS = 'export.bookmarks';
+    public const FEED_ATOM = 'feed.atom';
+    public const FEED_RSS = 'feed.rss';
+    public const IMPORT = 'import';
+    public const INSTALL = 'install';
+    public const LINKLIST = 'linklist';
+    public const LOGIN = 'loginform';
+    public const OPEN_SEARCH = 'opensearch';
+    public const PICTURE_WALL = 'picwall';
+    public const PLUGINS_ADMIN = 'pluginsadmin';
+    public const TAG_CLOUD = 'tag.cloud';
+    public const TAG_LIST = 'tag.list';
+    public const THUMBNAILS = 'thumbnails';
+    public const TOOLS = 'tools';
+}