[IMP] add default order parameter to list views

List views can now be sorted by default with a simple keyword 'order'.
For example

...
<field name="arch" type="xml">
    <tree string="Product Variants" order="name">
        <field name="name"/>
        ...
[IMP] add default order to kanban views

Now, the kanban view can be sorted by any field by default.  It just
needs to be given in the xml descriptor.  For ex,

<field name="arch" type="xml">
    <kanban order="country_id">
[IMP] improves the default order parameter

It is renamed 'default_order' and now supports the usual syntax for
sorting fields: for example 'field1, field2 desc, field3 asc'
Merge remote-tracking branch 'odoo/master' into master-default-order-list-ged
[IMP] improves sorting mechanisms in datasets

Create a deserialize_sort method and add a set_sort method to
datasets.  The set_sort method is useful to avoid duplicating code
in lists and kanban views (to set the initial default order)
[IMP] website: set geoip in user session
[FIX] website: geoip can't be none
Merge remote-tracking branch 'odoo/master' into master-default-order-list-ged
Merge remote-tracking branch 'odoo/master' into master-default-order-list-ged
[IMP] mail: added headers field on mail.mail, allowing to store headers data when sending notification emails.
merge upstream
Merge pull request #691 from odoo-dev/master-mail-headers-tde

[IMP] mail: added headers field on mail.mail, allowing to store headers data when sending notification emails. This commit in master improves the commit 839815fdd44742663742b3506329d5b46cb3e3f7 (saas-5) that was using computed but not stored values.
[REF] mail, crm, hr_recruitment, project, project_issue: simplified reply-to of notification emails (now displaying 'YourCompany -docname- <email>' instead of 'Followers of ...'; added same_thread directly on the mail.message model to ease the reply_to and message-id computation; factorized a bit the reply-to generation for a batch of records; udpated tests accordingly.
Merge pull request #520 from odoo-dev/master-default-order-ged

[MERGE] Add support for per-view default order in list/kanban views (task #8527)
Merge pull request #683 from odoo-dev/master-ref-reply_to-tde

[REF] mail, crm, hr_recruitment, project, project_issue: simplified repl.y-to of notification emails (now displaying 'YourCompany -docname- ' instead of 'Followers of ...'; added same_thread directly on the mail.message model to ease the reply_to and message-id computation; factorized a bit the reply-to generation for a batch of records; udpated tests accordingly.
Merge pull request #623 from odoo-dev/master-website-session-geoip-chm

[IMP] website: set geoip in user session
[FIX] move back setup to root
[FIX] git config for pull
Merge branch 'master' of https://github.com/odoo/odoo into master-kanban-column-reload-avo