allow contextual filter default value from raw url to also parse alias path

It came to my notice that when using a Raw Url default value for a contextual filter that Views will use the internal path (in my case node/x) instead of being able to extract a path component from the path alias I'm using. I would like to ask for this feature to be implemented for future versions.

I hacked plugins/views_plugin_argument_default_raw.inc, added a checkbox option to allow me to choose If I wanted to use the path alias and if the option is set i pass the return value of calling drupal_get_path_alias() as an argument to arg(). I could have created a different plugin but this way the contextual filter Global:Null also works. My changes are in the attached patch file so you can look at it.

I would like, if possible, to get some feedback if this might break something within Views, cause performance problems or if there might be a better approach for achieving this. If all is well, please consider adding this to future versions.

Best regards