bugfixes - auduit/turnaround_average date constraints passed spurious 'specimen' id; calculation of using_auth generated error if delta_authorise value was 0
aded ability to link lab tests; moved Moose attribute lab_test_map from M::Result to M::R::LabTestUpdate - also used by M::R::ResultUpdate, but relies on caller also loading M::R::LabTestUpdate; new test script to test linked lab-tests