Remove unused klass_args argument and avoid aborting transactions if
none is active. The publisher should always commit or abort the
transaction, so the Cleanup instance in `REQUEST._hold` shouldn't need
to abort anything. This gets rids of debug log messages, where each
request opens and aborts a secondary transaction.

Split a common base class out of them and move ZServer specific logic
onto HTTPResponse without impacting WSGIResponse.

Also change the error generating methods on WSGIResponse to raise
exceptions rather than returning responses. It's the publishers job
to turn them into responses and now they get treated in the same way
as when they get raised directly.

Quote variable in manage_tabs to avoid XSS [master]

From Products.PloneHotfix20160830.

This avoids the `repoze.retry` dependency for WSGIPublisher.

Also drive by fix for ZopePageTemplate.

Add new `ZPublisher.utils.recordMetaData` function to replace the
method previously found on the manager.

Change Testing to use the WSGI publisher for functional and testbrowser
based tests incl. functional doctests. Alternatives are available
in `ZServer.Testing`.

These need special casing in the publisher to be treated as successful
and result in transaction commits. Also prefer `raise Redirect` style
over `REQUEST.RESPONSE.redirect`.

Opened database are now found in `Zope2.opened` next to `Zope2.DB`.
Also stop setting client/instance home variables onto `__builtin__`,
those are available from `App.config.getConfiguration()` as
`instancehome` and `clienthome` attributes.

Based on zopefoundation/five.pt@197e65819013fbfd3a436286737f20ddc4c48813.