- DateTimeKey does not accept None, explitly use a DefaultKey for this
- if no organisations are member of the selected group, then default_destination_section_uid=[] will be used, which is skipped by catalog, use default_destination_section_uid=-1 not to match any
- if an order with no date was selected, then calling strftime failed

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@26019 20353a03-c40f-0410-a6d1-a30d3c3de9de