If a section tells the transmogrifier about the created archive
(by calling transmogrifier.add_info('export_content', name, info), e.g.
at the end of the __iter__ method), the calling method can return this
archive to the user for download. This way, transmogrifier turns into a
tool which can be offered to "normal" users for flexible exports,
without the need to edit the pipeline configuration first.

Here is all the meat!

Produces a pretty string which represents the _all attribute of a
Transmogrifier object.  Can return a list instead.

Conflicts:
	src/collective/transmogrifier/utils.py

When ConfigurationRegistry.clear is fired unexpectedly, this can go
unnoticed and cause transmogrifications to fail.  Thus, this can be
customized by setting the CLEANUP variable.

To suppress the call by the zope.testing.cleanup facility entirely, this
variable must must be changed to OFF in the module code, because this is
done on import time.  For other uses, the variable can be set after
importing.

The present SILENT value reflects the so-far behaviour.

Conflicts:
	src/collective/transmogrifier/transmogrifier.py