Integrate changes for OVPMS-1517Add a new Discount type to produce a discount based on cost price plus a rate, contributed by Ben Charlton

git-svn-id: svn://svn.openvpms.org/openvpms/vpms/trunk@6196 9e4fa352-aafb-0310-9071-df624684024b
Fix to use the fixed and unit cost stored on the item rather than those on the price; this may change or not be available if:
* the unit or fixed price changes
* the customer has tax exemptions

git-svn-id: svn://svn.openvpms.org/openvpms/vpms/trunk@6198 9e4fa352-aafb-0310-9071-df624684024b
Changes for OVPMS-1522 Work In Progress location filter

git-svn-id: svn://svn.openvpms.org/openvpms/vpms/trunk@6199 9e4fa352-aafb-0310-9071-df624684024b