Try to save memory and time when using lazy objects by refering to their...

Try to save memory and time when using lazy objects by refering to their function via the closure, and not making it an attribute on each instance.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17360 bcc190cf-cafb-0310-a4f2-bffc1f526a37