Cleanups to related manager code, especially in use of closures.

The related manager classes are defined within functions, and the methods
had inconsistent and confusing usage of closures vs. parameters on self to
retrieve needed information. Everything is stored on self now.

Also some methods were not using super() where they should have been.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16913 bcc190cf-cafb-0310-a4f2-bffc1f526a37