Merged back changes for OVPMS-1522 Work In Progress location filter

git-svn-id: svn://svn.openvpms.org/openvpms/vpms/branches/1.8-dev@6205 9e4fa352-aafb-0310-9071-df624684024b
Integrated changes for OVPMS-1519 Relative Date extensions contributed by Tim Gething

git-svn-id: svn://svn.openvpms.org/openvpms/vpms/branches/1.8-dev@6206 9e4fa352-aafb-0310-9071-df624684024b