Merge branch 'master' of git://github.com/melinath/philo

* 'master' of git://github.com/melinath/philo:
  Added feed length limit to FeedView. Implements feature #111.
  Corrected LazyNavigationRecurser to mark its return value as safe.
  Switched back to setting a {{ children }} variable, but set it to a lazy recurser instead of a rendered result. Switched item and children to be set in the context directly for easy access. Improved/updated recursenavigation docstring.
  Refactored the RecurseNavigationNode to have less repetition. Switched from {{ children }} to {% recurse %} because it makes more sense to collect recursion only if needed.
  Added a number of counting variables to the context when rendering shipherd navigation. Designed to mirror the variables generated when using a for loop.
  Minor corrections to shipherd recursenavigation docstring.
  Added CSRF cookie js to TagCreation.js... apparently it isn't in the admin by default. Resolves issue 83.
  Added an admin action to NewsletterArticleAdmin to handle creating a NewsletterIssue from a selection of articles. Resolves issue 82.
  Minor LazyContainerFinder cleanup. It's not really that lazy in practice...
  Removed nodelist_crawl since nothing is using it and I'm starting to question its usefulness in general.
  Built a clearer algorithm for finding a template's containers; added support for template block overrides cancelling out containers in that block, which resolves issue #90.
  Corrected FeedView handling of incorrect Accept headers. Will now actually return 406 errors.
  Genericized nodelist_crawl to just pass each node to a callback function. Overloaded the Template.containers callback to create a blockcontext for handling containers in overridden blocks as per issue 90 and to handle contentreference/contentlet generation in a single sweep.
  Refactored ContainerForms to reflect a more suitable structure by storing the containers internally as a SortedDict. By handling containers more consistently, this commit resolves issue #89.
  Removed apparently-vestigial Entity.attribute property.