migratePortalType will create new document with expected portal_type and delete the current one (ie. self)

Before returning new one, workflow states will be synchronised (if possible).
Related relations will be keept up to date.





git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@40959 20353a03-c40f-0410-a6d1-a30d3c3de9de