more patches to cron scripts - all date subtractions performed on a new time_now() object in ScriptHelpers::date_subtract(), NOT on the local object in case it's used again after the DT subtract() function performed}
git-svn-id: https://jti.org.uk/svn/hmds_lims/trunk@1203 4177bd82-f056-0410-812d-caef170e3fa0
