Fix a problem with apply trade condition, with the previous changes it was not able to find a trade condition if no categories were defined on the order.
Also change the weighting method so that mirror node and mirror section only add weight if they correspond to what's defined on the order.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@25178 20353a03-c40f-0410-a6d1-a30d3c3de9de