Sluggable-mixin

I've extracted the slug-related code from this blogging software and packaged it so that it should be easily-portable to any Google AppEngine application.  I hope that it will be useful for anyone who needs to add nice human and search engine-friendly URLs to their app.  It works like and is similar in spirit to my previously-released AppEngine mixin, taggable-mixin.

I'd like to encourage anyone who finds this useful -- or any who finds it to be a useless atrocity -- to leave questions, suggestions and feedback here.  I will answer as quickly as I can.