- set manually the quantity on lines, it is not calculated automatically
  any more by default with the list of items.
- make sure to not create again the currency when it is already there
- do not set the inventory property on inventory line, this is useless
  and deprecated

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@27689 20353a03-c40f-0410-a6d1-a30d3c3de9de