Fixed #9284. Fixed #8813. BaseModelFormSet now calls ModelForm.save().

This is backwards-incompatible if you were doing things to 'initial' in BaseModelFormSet.__init__, or if you relied on the internal _total_form_count or _initial_form_count attributes of BaseFormSet. Those attributes are now public methods.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10190 bcc190cf-cafb-0310-a4f2-bffc1f526a37