Add %nid as a token replacement options

I would like to be able to send a direct link to the edit screen in my moderation approval messages. When using pathauto, the %node_url token expands out into the pathauto generated path, which for the most part is what one wants. Where it does not work for me is that I want to construct the http://www.site.com/node/1234/edit form of the node, which cannot be done based on %node_url.

The attached patch is a one-line addition: it adds a %nid token to the list of valid tokens for the moderation mail. I use this to create the /node/1234/edit form of the URL.