[FIX] point_of_sale: uncrash widget.js

Error during forward port
[IMP] project: onboardin / usability improvements

- project kanban view: dashboard-like view, add sparklines for open tasks
and closed issues
- project: cleaned demo data, less stages
- project: description is now an html field
[FIX] res_users: set login_date as datetime instead of date

To allow display the login date according to the timezone of the user
[IMP] project: project alias generation is True by default.
[IMP] project: better diplay of task/issue title
[ADD] Add an html compressor option in website settings
[IMP] CRM Onboarding improvement
[IMP] sale_stock: warehouse_id field on sale order is now readonly, except in draft and sent states.
[IMP] accounting: modify writeoff_amount display in payment wizard
[FIX] website_mail & calendar: demo data break the layout of mail design
[FIX] website_mail: can't be edit the mail template, javascript must be added into the asset
[FIX] website: remove multi consecutive dropzone
[FIX] snippets: use the new API to define dropzone
Merge pull request #2547 from odoo-dev/master-fix-mass-mailling-snippet-chm

[FIX] website_mail: can't edit mail templates
[IMP] web client refactoring: action and view manager

large rewrite of action manager, view manager and
viewmanageraction.  The goal is to lay the foundation
for the redesign of the advanced search view.

This commit includes:
* improvements to the display order (no/less flickering)
* large simplification of the breadcrumbs code
* much better html layout for the header (no table)
* bootstrapisation of the view manager
* lots of optimizations/simplification
* a base.css.map, courtesy of the last sass version
[FIX] fixes many issues with the various views

the views don't always return a proper promise, or were
somewhat fragile and broke with the changes in the view
manager.
[IMP] readd pager functionality to web client

The pager was removed in the refactoring of view manager. This commit
readd the pager, and improves its rendering to avoid flickering
[IMP] graph view integration into view manager header
WIP
css tweaks