Fix some hackificator odds and ends in wp-admin:

* `wp-activate.php` and `wp-admin/themes.php` don't need the closing PHP tag
* Switch single quotes for HTML attribute values to double in a few places
* Convert `include_once file.php` syntax to `include_once( 'file.php' )`
* Add access modifiers to methods/members in: `_WP_List_Table_Compat`, `Walker_Nav_Menu_Edit`, `Walker_Nav_Menu_Checklist`, `WP_Screen`, `Walker_Category_Checklist`
* `edit_user()` doesn't need to import the `$wpdb` global
* `wp_list_widgets()` doesn't need to import the `$sidebars_widgets` global
* switch/endswitch syntax is not supported in Hack
* A `<ul>` in `wp-admin/users.php` is unclosed

See #27881.

Built from https://develop.svn.wordpress.org/trunk@28500


git-svn-id: http://core.svn.wordpress.org/trunk@28326 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/network/upgrade.php

@@ -86,7 +86,7 @@ switch ( $action ) {
 		}
 		echo "</ul>";
 		?><p><?php _e( 'If your browser doesn&#8217;t start loading the next page automatically, click this link:' ); ?> <a class="button" href="upgrade.php?action=upgrade&amp;n=<?php echo ($n + 5) ?>"><?php _e("Next Sites"); ?></a></p>
-		<script type='text/javascript'>
+		<script type="text/javascript">
 		<!--
 		function nextpage() {
 			location.href = "upgrade.php?action=upgrade&n=<?php echo ($n + 5) ?>";