Fix error "Only variables should be passed by reference" in cosmogramme

cosmogramme/php/_init.php

@@ -33,7 +33,8 @@ while( true ){
 	if (chdir("../") == false) exit;
 }
 
-define('BASE_URL', '/'.end(explode('/', dirname(realpath('.')))));
+$parts = explode('/', dirname(realpath('.')));
+define('BASE_URL', '/'.end($parts));
 define('USERFILESPATH', '..' . '/userfiles');