removed reference/s to demoted MSGID_MULTIPLE_AT

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1586579 13f79535-47bb-0310-9956-ffa450edef68
improvements for disabled plugins

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1586581 13f79535-47bb-0310-9956-ffa450edef68