[MERGE] [FIX] mail: attachments in pure email mass mailing.

[MERGE] [FIX] mail: attachments in pure email mass mailing.

When generating pure email mass mailing, the values are directly sent to mail_mail.create() instead of going through mail_thread.message_post(). We therefore have to process attachments (coming from email_template, as a list of tuples (attachment_name, b64-encoded attachment_content)) as well as attachment_ids, like it is done in message_post.
As this behavior is the same as the one already implemented for message_post, this feature has been moved into its dedicated method called by message_post or called before going into mail_mail.create(), depending on the mailing type.

[FIX] email_template: when generating reports in batch, correctly attach the generate attachments to the various record ids we are iterating on.

bzr revid: tde@openerp.com-20131129094406-90cijc5ac4pmp4y7