The choice of filename `redirect.local.conf`is just only my preference. I understand (at least for me as a Wiki admin) that local files are to be prepared by the Wiki Admin 
and are not included in the core package. This view may be different from core developers.

Exactly no default file will used, the lines include `'default' => ` can be removed from admin.php and action.php file.

I do not know any guidance on how admins should use the conf folder except plugin_lang folder, user's css and javascript. Some confliction among plugins may arise if they use same file in the conf folder. I thought this is a reason why the original redirect plugin store its conf file in the plugin folder.
Any idea?