Put version 1.6.0 in trunk

git-svn-id: https://plugins.svn.wordpress.org/square-sidebars/trunk@964183 b8457f37-d9ea-0310-8a92-e5e31aec5664
Import version 1.6.0

git-svn-id: https://plugins.svn.wordpress.org/square-sidebars/trunk@964184 b8457f37-d9ea-0310-8a92-e5e31aec5664