add a new property create_line used to indicate if we want to create movement corresponding to this model line or not.
This is usefull in case of "intermediate lines" : a line we want to participe on some base_amount without being created.


git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27365 20353a03-c40f-0410-a6d1-a30d3c3de9de