product_template inheritance: added email_template_id field, link to an optional email.template
invoice inheritance: when validating the invoice, send an email for each product that has a linked email.template.
email_template inheritance: defined a new simplified form view with only attachment_ids and body, to ease the quick edition of email templates. This simplified form view is used for the email_template_id field on the product.template form view.
email_template: when having default_model in default_get, use it to prefetch model_id. Indeed model is a related file, we have to redirect its default to the right model_id field.
bzr revid: tde@openerp.com-20140124120652-vxp0jwf14sl1frme
Kersten Jeremy
Olivier Dony
Christophe Simonis
Thibault Delavallée