Fixed #11134: signals recievers that disconnect during their processing no longer mess things up for other handlers. Thanks, Honza Kral.

While I was at it I also cleaned up the formatting of the docstrings a bit.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@10831 bcc190cf-cafb-0310-a4f2-bffc1f526a37