A few x2many list embedded in form views have the "editable" attr
set to "1". Normally, the valid values for this attribute are "top"
and "bottom". Regular list views are validated, but not lists
inside form views.
When set to "1", some features of the model aren't enabled. For
instance, when the current page is full and the user adds a record,
the limit isn't temporarilly increased for the added record to be
displayed on the current page, like it would be in editable="bottom"
lists, so the user doesn't see the record he just added.
The issue can be observed in the stock move form view for instance.
This commit is only good for stable versions: we add a fallback
on "bottom" s.t. if the editable attribute is set, it's always
either "top" or "bottom".
In master, we'll probably rethink the API.
opw~3860903
closesodoo/odoo#162832
Signed-off-by: Lucas Perais (lpe) <lpe@odoo.com>