inform7-mode

Hi, I've added a recipe for inform7-mode (https://github.com/fred-o/inform7-mode), of which I am also the author. It's a simple major mode for editing Inform 7 (http://inform7.com/) source files. I blogged a bit about it here: http://fredrik.appelberg.me/2012/03/05/let-s-write-an-emacs-mode-for-inform-.html