The main purpose of this commit is to be consistent with the enterprise edition,
in which the event 'DOM_updated' is triggered when new content is inserted in
the DOM. This way, addons that need to know when a view has been attached in the DOM
(e.g. web_tip) can listen to this event and will work fine with both editions
of the web addon.
With the actual structure of the webclient (action_manager, view_manager),
there is no easy way to decide whether or not a view is attached in the DOM,
because every rendering is performed in a detached element. For instance,
when a view_manager instantiates a new view, it appends it in its $el once
the view is ready, but it can't know if its $el is attached in the DOM (it is
only the case if the view_manager is the current action of the action manager).
This rev. introduces utility functions to centralize the appending/prepending of
content, so that an event can be triggered (at a unique place) when the content
is really in the DOM. These functions are used by the the action_manager and the
view_manager.
Another change is that the action_manager keeps the view_manager informed when
they are attached in/detached from the DOM, through the variable is_in_DOM.