implementation from Zope 3.

that the publishTraverse method on the Zope3 implementation, which we use now,
works as expected).

it with light shims over the Zope 3 stuff.

Moved special __parent__ behaviour up to the browserview class, so all classes inheriting from it, gain this special behavior.

browserDefault implementations that were returning object_thats_not_self, ()
didnt' work.

towards OFS.Traversable and OFS.Application. Name them so.

Introduce a more generic implementation that's very very close to the Zope 3
one and works on objects that don't inherit from OFS.Traversable or support
acquisition (e.g. views, resources, etc.)