Helper for "get_something as varname" template tag pattern
|Ready for checkin
|Patch needs improvement:
It's a common pattern to write a template tag that fetches some data and sticks it in a context variable. Currently writing these tags requires writing a full-blown parsing function and Node class, which is mostly boilerplate except for the render() method. It would be good to have a template tag helper for writing tags that follow this pattern. (Similar to simple_tag, except allowing for updating the context).