add new step and new tests. This tests check that it's possible to have...

add new step and new tests. This tests check that it's possible to have model_line that depend each other in both cases :
1 - if the model line creation order follow the dependencies, there should be no problem
2 - if the model lines are randomly created (ie, if you create first a line A wich applied on base_amount X, and after you define the line B wich contribute to base_amount X)

in both cases, getAggregatedAmountList should be able to return the same result


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27337 20353a03-c40f-0410-a6d1-a30d3c3de9de