This commit adds a new QWeb layout mail_notification_light. It is a new
lighter template using more modern styling. Its purpose is to be used as
a basis for all future templates used in notification mechanism (chatter,
sale orders, ...). During some time all templates will exist separately.
Future commits will gradually improve or add various notification
mechanisms. This new template will gradually be used more often in order
to replace old ones.
Thanks to @est-odoo for its in-depth testing of the template.
Thibault Delavallée
2709ffe0e2