Add ve.ce.View as a common base class for ce.Node and ce.Annotation

Just like ve.dm.Model is a common base class for dm.Node, dm.Annotation
and dm.MetaItem.

ce.View abstracts the this.model and this.$ behavior, including liveness,
whitelisted HTML attribute rendering and adding a back reference in
.data(). The back reference has been renamed from .data( 'node' ) to
the more generic .data( 'view' ).

At this point this means ce.Annotation is just a shell around ce.View
(except where it defaults to a span rather than a div), but that could
change in the future.

Change-Id: I0eef5b80718e0b0fcd3f8bba096b452f0bb680d0
Merge "Add ve.ce.View as a common base class for ce.Node and ce.Annotation"