Add QuantityUnitMovementGroup, suggested by Romain.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@14826 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/MovementGroup.py

@@ -1105,3 +1105,7 @@ class RequirementMovementGroup(RootMovementGroup):
   def test(self,movement):
     return self.getRequirementList(movement) == self.requirement_list
 
+class QuantityUnitMovementGroup(PropertyMovementGroup):
+  """ Group movements that have the same quantity unit."""
+  _property = 'quantity_unit'
+allow_class(QuantityUnitMovementGroup)