- Now Sympa::Bulk::store() returns messagekey instead of "1" when it succeeded.
- Return-Path of outbound messages will be taken from {envelope_sender} attribute of the message object.
- Priority of them will be taken from {priority} item.
- {date} item is used for delivery date.
- use_bulk flag for Sympa::Mail::sending() was deprecated.  Sympa::Bulk::store() would be called directly.


git-svn-id: https://subversion.renater.fr/sympa/branches/sympa-6.2-branch@11373 05aa8bb8-cd2b-0410-b1d7-8918dfa770ce