Now that trade model lines are built, they are included in
invoice.getTotalPrice, so instead we manually sum all movements that are not
tax or resource.
The problem is that this test is now more complex than the code beeing tested



git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@28753 20353a03-c40f-0410-a6d1-a30d3c3de9de