Fixed #11021 -- Clarified newline stripping behavior in the truncatewords and...

Fixed #11021 -- Clarified newline stripping behavior in the truncatewords and truncatewords_html filters. Thanks to Ben Spaulding for the report and patch.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@13555 bcc190cf-cafb-0310-a4f2-bffc1f526a37