[IMP] web: new pivot view, full rewrite of graph view

This commit is a split of the former graphview into a pivot view (the
tabular view) and graph view (the various charts).  The code was fully
rewritten.
* pivot view should be faster (better underlying data structure and
better algorithm)
* better integration with the web client (use of sidebar, of menu buttons,
bettor style)
* new feature: pivot view can be sorted
* new feature: pivot view cells can be clicked to open a list view with
the corresponding domain
* web_graph addon was removed, and the graph view code has been moved
to the addon web.
* the interaction with the searchbar was changed (no more column facet)
* better and simpler code for graph view
* mary corner cases in graph charts have been corrected (for ex, pie
chart with positive and negative numbers)
* graph/pivot correctly save their state when added to dashboard/saved
(state such as current measure, chart mode, column groupbys, ...)
[IMP] account: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[FIX] board: add to dashboard now uses correct context
[IMP] crm: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[IMP] event: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[IMP] fleet: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[IMP] hr: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[IMP] project: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[IMP] various addons: add pivot views next to graph views

The graph view has been splitted into pivot/graph view.  This commit add
a pivot view whenever a graph view was defined.
[MERGE] Merge branch 'master-pivot-view-ged'

close PR #4350

split graph view into pivot view and graph view: new pivot
view and full rewrite of graph view.

* pivot view should be faster (better data structure and
  algorithms
* better integration with the web client (sidebar, buttons,)
* new feature: pivot view can be sorted
* new feature: pivot view cells can be clicked to open a list
  with the corresponding domain
* the interaction with the search bar was simplified
* better and simpler code for graph view
* many corner cases in graph charts have benn corrected (for
  example, pie charts with positive/negative numbers)
* graph/pivot correctly save their states when added to
  dashboard/saved (state such as current measure, chart mode,
  column groupbys, ...)
[FIX] web: clicking on view buttons now refresh view

clicking on a view button should load the view, even if it is the
active view.
[IMP] ir_attachment : support both python-magic lib (pypi and file) to determine mimetype. Since the 2 lib don't have the same method, we need to find which one is imported. magic is still an optional dependency.
[FIX] REGEX on <a> links only + don't pass several times on the same link