Oktavilla/Porthos-Engine — pull request #157 by arvida (2013-06-14 12:28:04+00:00)
Title: Caching shell objects touches it shell on touch

This resolves a bug discovered in the Unicef project
(https://trello.com/c/QFo9R6vA): a object that belongs to a parent object
that includes CachingShell didn't update the parents cache key when the child object
touched the parent.