[1.2.X] Fixed #15569 -- Corrected the numbering updates to inlines when rows...

[1.2.X] Fixed #15569 -- Corrected the numbering updates to inlines when rows are added and deleted. Thanks to sbaechler for the report, to Arthur de Jong and mk for the work on the patch, and to Karen Tracey for the last minute testing help.

Backport of r15862 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@15863 bcc190cf-cafb-0310-a4f2-bffc1f526a37