This commit introduce a full redesign of all JS views.  We started
basically from scratch.  The goal was to unify all the various views
under a common framework, to make them testable, to make then usable in
different conditions (in studio, or in the frontend), and to make our
lives easier.

Some important points are:
- we introduced new coding guidelines (camelCase, 80 chars width, ...)
- we have a brand new testing framework (still QUnit based)
- kanban view moved to the web addon
- calendar view (formerly web_calender) moved to web as well
- the tree view was removed
- all new code should be documented

We hope that this code is the start of a new era for the Odoo web
client, we want to have a high quality codebase, well documented, well
tested, well designed.

Work done by the framework team: mostly aab, ged, chm, dmo, qsm

ir.needaction_mixin is not used anymore by the webclient.
From 9.0, the concept has changed: this feature is now
available in mail module, with the mail.thread mixin,
and message_neeadction field.

Remove all code handeling needaction bullet and
counter on ir.ui.menu, knowing that since 9.0
webclient does not display the counter anymore.

This code was, thus, useless and some RPC calls
were done for nothing, and adapt accounting
reconcialiation widget.

* Tip are never destroyed when change view mode
* unbind methods
* mail: memory leak with unbind methods
* web: memory leak because 'ui-autocomplete' is never destroyed
* web_editor: memory leak for wrong unbind on destroy
* web: memory leak: must remove fileupload handler
* bus: memory leak: correctly debind handlers on window in bus.Bus
* remove handlers on switch buttons and views $buttons
* remove handlers on breadcrumbs
* web: memory leak: correctly debind handlers
* im_odoo_support: memory leak: remove fileupload handler odoo_support

Note: part of this commit was actually authored by aab

Commit of xmo that has been lost by the unduplication of webclients (6768bbfc).

Avoid duplicating web addon in enterprise by extracting a common basis.
Enterprise features stay in enterprise, but use that common basis.

Mainly:
 - JS refactoring and linting
 - Conversion of .sass into .less split into multiple files
 - Templates cleaning and DOM simplification
 - Re-generation of web.pot, and update of .po files

Introduction of 'data_manager' service which handles meta-data related to
actions and views (fields_views, fields and filters). Ideally, all RPCs to
get that kind of information should go through data_manager, as it holds an
internal cache.

Load the fields_view of all views of the action together. If a searchview is
required, also load its fields_view and its filters.

Use lazy-loading for fields as they are required for the Pivot and Graph
views only, and may be used by Filters and GroupBy menus of the Search view
if the users clicks on 'Add a custom Filter/Group'.

The fields are thus also loaded directly if the first view of the action is
Pivot or Graph, and otherwise, they are lazy-loaded when/if the user opens
a Pivot or Graph view, or if he wants to add a custom Filter/Group.

Some refactoring of views API as well:
- Views must now be instantiated with their fields_view
- Move code requiring fields_view from start() to init(), or willStart() for
  heavy processing.
- Remove view_type attribute from views as it was used to call
  fields_view_get.
- Remove view_id parameter to views' init as it is no longer used.
- Move duplicate code from various views' init to the View widget.
- Remove view_loading() function from views as they now follow the classical
  lifecycle of widgets (init -> willStart -> start -> destroy).
- Searchview now extends View like all other views.
- Remove useless function guard_active() as it was used for the form_view's
  action buttons to wrap handlers to ensure that they are executed only if
  the form_view is the current active view. This is not useful anymore as
  from v9, views and their control panel are appended in the DOM
  simultaneously, so one can't click on a button of a view which is not the
  current active view.

unused since rev. odoo/odoo@4a5cb1ebc478cb650a2bf33081f101e4f74bc6fe.