smtp debug and cron jobs improvements

git-svn-id: https://plugins.svn.wordpress.org/sendit/trunk@861311 b8457f37-d9ea-0310-8a92-e5e31aec5664
newsletter duplication for test sending

git-svn-id: https://plugins.svn.wordpress.org/sendit/trunk@865004 b8457f37-d9ea-0310-8a92-e5e31aec5664