[IMP] website.snippet: snippets can be splitted into separate template and be called into the lits of the snippet

Add an invisible field `pricelist_id` to project.project form view, so that when
`partner_id` is changed, `onchange_partner_id` method can also set the
pricelist properly (previously, the pricelist was not set because the
field was not in the view).

Adding <span>'s inside the <p> will allow the translation editor to
distribute the right branding on the strings to be translated.

[IMP] crm: change label of 'probability' field and display 'Customer' in search instead of 'Partner'

[IMP] base, ir_sequence: removed ir.sequence.type object, added test for ir.sequence.date_range, refactored ir.sequence and ir.sequence.date_range implementation

This module tracks clicks in mass mailing mails and allow the generation of trackable links in a website interface.

Modules modifications
---------------------
Refractoring of the crm_tracking_* classes in a new module.

* Extract the crm_tracking_* from the crm module into a new module "utm"
* Remove the crm_mass_mailing bridge module
* New dependencies of mass_mailing and website_links to utm.

[IMP] When no stock moves, change whatever you want, otherwise no change at all for UoM.  #3440 Enhancement request richard-willowit

The default UoM can only be changed when there are no stock moves (or only cancelled ones), but to any category.
The purchase UoM can be changed whenever you want, but has to be in the same category as the default UoM.

Closes #3440

[IMP] When no stock moves, change whatever you want, otherwise no change at all for UoM.  #3440 Enhancement request richard-willowit

[FIX] Remove line

[FIX] Constraint should be applied when UoM or PO UoM is changed

[IMP] account/sale/sale_layout: standardization of Quotation/Sale Order/Invoice printed layout + add missing information

- Column alignment and order are now uniform across those reports.
- Display Due date on invoices.
- Display payment term and fiscal positions notes.

[FIX] point_of_sale: by default cash is returned on the payment method with cash control. If there is no such method, return it on the the first cash payment method

[FIX] pos_restaurant: properly merging the notes feature that allows custom notes on orderlines (Think Raw/Well-Done)

[FIX] pos_restaurant: please stop forward porting the obsolete 'restaurant' module. It has been renamed pos_restaurant

Fixes #4203

[IMP] ir.attachment : move the fields index_content (from document), mimetype and datas_checksum (from website) to base. In base, the mimetype is computed with the Magic python lib (if installed, else with a custom function using magic number), and the index_content is an implementation of strings unix command. In document, index_content is still computed with the indexer of document module.

on links in forum posts.

This is now done when creating / updating posts instead of updating the display
of the post. This means that old posts may contain nofollow attribute altough
the user has sufficient karma; however it is acceptable compared to the computation
we save by avoiding processing every post to display.

* ir_actions_common should return a deferred : some widgets
  do not return a deferred in start, so it could be undefined.
  it now is always a deferred.
* add icon for diagram view + breadcrumb support. diagram view
  is so rare that it wasn't tested in the client refactoring.
  This patch adds an icon for diagram view, and better support for
  breadcrumbs
* add warning in debug mode print workflow: when no record is
  selected, display a warning instead of failing silently

[IMP] website_sale : improve domain for not set category in product from frontend  and remove other demo data of public categories

the method prepare_dropdown_menu wasn't called when the searchview did
not have an action id.  This can cause problems in some cases (for
example, a crash in messaging when toggling the favorite menu)

Big Point of Sale Update !
==========================

 - Loyalty module for loyalty cards and loyalty rewards
 - Restaurant module has floor plans, and floor plan editor
 - Restaurant module has orderline notes ( Bloody / Well Cooked ... )
 - Customers can be created from the point of sale
   * You can take customers picture from Android / iOS
 - In-progress orders are kept between crashes and restarts
 - Barcode Nomenclatures support complex and custom barcode systems
   * Shared configuration with the WMS.
   * Product weight support in the WMS UI.
   * Multiple barcodes for the same product via barcode aliases
   * EAN-13 constraint removed, no more internal-code hacks.
 - Cashier Login / Logout from the point of sale with pin codes
   * a JS sudo() interface to help integrators customize the point
     of sale security:

    this.pos.sudo().then(function(){
        ... // only POS Managers can do this.
    });

 - QWeb receipt customisation for header and footers :
   * You can now include barcodes & other complex info, without
     new modules with the `<!DOCTYPE QWEB>` prefix in textareas :

     <!DOCTYPE QWEB>
     <div>
        <t t-esc="Math.random() + 'foobar'" />
        ...
     </div>

 - Lots of fixes & Usability improvements from customer feedback.
 - New demo data will come in a later commit.