Fixed #6197 -- Added (optional) formfield_callback argument to...

Fixed #6197 -- Added (optional) formfield_callback argument to ModelForms.__new__. Patch from guido@python.org.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@6940 bcc190cf-cafb-0310-a4f2-bffc1f526a37