Sort predicates by int_index and id in when getting a list of ids of quantity predicates. Also, make sure that getQuantityPredicateValueList does retrieve only sub-objects.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34139 20353a03-c40f-0410-a6d1-a30d3c3de9de