Deprecate inconsistent API to extend the navigation by local plugins

You can use this very minimalistic plugin local_demo: <?php // version.php ///////////////////////////////////////////////////////////   $plugin->version = 2015032300;     <?php // lib.php ///////////////////////////////////////////////////////////////   function local_demo_extends_navigation(global_navigation $navigation) { $navigation->add('Demo!'); }   function local_demo_extends_settings_navigation(settings_navigation $settings, $context) { if ($node = $settings->get('usercurrentsettings')) { $node->add('Awesome!'); } }     <?php // lang/en/local_demo.php ////////////////////////////////////////////////   $string['pluginname'] = 'Demo local plugin'; Play with the file lib.php and make sure that both variants 'extends' and 'extend' actually work and the new texts appear in the blocks. Make sure that the deprecated variant throws DEBUG_DEVELOPER message. Make sure that if both current and deprecated variants exists, the current is used and no deprecation warning is displayed.