- When deleting duplicate messages, keep the one the highest score (priority,
  date, uid).
- When several messages have the same serialization_tag, always validate first
  the one with the highest score.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@34632 20353a03-c40f-0410-a6d1-a30d3c3de9de