Enable localization of special page.

- Improved: Special Page can now be translated using messages.

includes/Extension.php

@@ -27,6 +27,7 @@ namespace LinkTitles;
  * Provides event handlers and entry points for the extension.
  */
 class Extension {
+	const URL = 'https://github.com/bovender/LinkTitles';
 
 	/**
 	 * Event handler for the PageContentSave hook.