Master slides rga

- Task: https://www.odoo.com/web?debug=#id=9093&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.QlQTvBv6mCcMrK4B
Adding messaging on attachments seems a really bad idea to me. For access rights, you will check access on attachments that will delegate to the related documents ... I bet you will face bad performances.