A handful of fixes to django.contrib.comments:

  * Fixed #9143, #9429, and #9439 (was r9730 on trunk)
  * Fixed #9959: comment preview documentation example (was r9731 on trunk)
  * Fixed #9346: comment upgrade SQL in documentation. (was r9732 on trunk).

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.0.X@9738 bcc190cf-cafb-0310-a4f2-bffc1f526a37