Before this rev. one could set the report layout on the company using a
hardcoded list (background, clean, standard, etc.). Other modules (typically
accounting modules) could add options in this list. The used template was built
on the layout key.
Now, the layout is a many2one field to a newly created model `report.layout`,
which is linked to a view with the layout architecture.
This gives more control to customize reports and create a new layout (without
creating a python module that extend the layout selection).
Christophe Matthieu
61eef73b52