- New API: ``pyramid.config.Configurator.add_notfound_view``.  This is a
  wrapper for ``pyramid.Config.configurator.add_view`` which provides easy
  append_slash support.  It should be preferred over calling ``add_view``
  directly with ``context=HTTPNotFound`` as was previously recommended.

- New API: ``pyramid.view.notfound_view_config``.  This is a decorator
  constructor like ``pyramid.view.view_config`` that calls
  ``pyramid.config.Configurator.add_notfound_view`` when scanned.  It should
  be preferred over using ``pyramid.view.view_config`` with
  ``context=HTTPNotFound`` as was previously recommended.

- The older deprecated ``set_notfound_view`` Configurator method is now an
  alias for the new ``add_notfound_view`` Configurator method.  This has the
  following impact: the ``context`` sent to views with a ``(context,
  request)`` call signature registered via the deprecated
  ``add_notfound_view``/``set_notfound_view`` will now be the HTTPNotFound
  exception object instead of the actual resource context found.  Use
  ``request.context`` to get the actual resource context.  It's also
  recommended to disuse ``set_notfound_view`` in favor of
  ``add_notfound_view``, despite the aliasing.

- The API documentation for ``pyramid.view.append_slash_notfound_view`` and
  ``pyramid.view.AppendSlashNotFoundViewFactory`` was removed.  These names
  still exist and are still importable, but they are no longer APIs.  Use
  ``pyramid.config.Configurator.add_notfound_view(append_slash=True)`` or
  ``pyramid.view.notfound_view_config(append_slash=True)`` to get the same
  behavior.

- The ``set_forbidden_view`` method of the Configurator was removed from the
  documentation.  It has been deprecated since Pyramid 1.1.

- The AppendSlashNotFoundViewFactory used request.path to match routes.  This
  was wrong because request.path contains the script name, and this would
  cause it to fail in circumstances where the script name was not empty.  It
  should have used request.path_info, and now does.

- Updated the "Registering a Not Found View" section of the "Hooks" chapter,
  replacing explanations of registering a view using ``add_view`` or
  ``view_config`` with ones using ``add_notfound_view`` or
  ``notfound_view_config``.

- Updated the "Redirecting to Slash-Appended Routes" section of the "URL
  Dispatch" chapter, replacing explanations of registering a view using
  ``add_view`` or ``view_config`` with ones using ``add_notfound_view`` or
  ``notfound_view_config``