Make sidebar toggle elements configurable

Current options are h1, h1 and h2, h1-h5, top-level list items

SPR-754

conf/metadata.php

@@ -1,14 +1,11 @@
 <?php
-/*
- * configuration metadata
- *
- */
 
-$meta['logo']             = array('string');
-$conf['logo_spacer']      = array('string');
-
-$meta['discussionPage']   = array('string');
-$meta['userPage']         = array('string');
-$conf['user_ns']          = array('string');
-$meta['hideTools']        = array('onoff');
-$meta['tasks_page']       = array('string');
+$meta['sidebar_sections'] = array(
+                                'multichoice',
+                                '_choices' => array(
+                                    'h1',
+                                    'h1,h2',
+                                    'h1,h2,h3,h4,h5',
+                                    'li.level1 > .li',
+                                ),
+                            );