Tie off release 1.6

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1587352 13f79535-47bb-0310-9956-ffa450edef68
Prepare trunk for 1.7 development

git-svn-id: https://svn.apache.org/repos/asf/manifoldcf/trunk@1587354 13f79535-47bb-0310-9956-ffa450edef68