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

Underscore method _.each expects an array like object when a
"length" property is present.

This was an issue with a record having a numeric "length" field set
to a non-negative value.

opw-691070

When we drag and drop a record in a folded column, the number of elements
in this column displayed  in the column title is not updated.
This issue is present because when a record is droped in a column
its id is not added to the dataset of its new column.

To fix this, we had to add the id of the record in the dataset, and
override the method 'add_ids' in 'DataSetSearch' to have the size
of the dataset equal to the number of ids in it. We have replicated
the behaviour of the function 'remove_ids' in the new function 'add_ids'.