OpenSystemsDevelopment / qpdf

This results in measurable performance improvements to packaged binary
libqpdf distributions. QTC remains available for library users and is
still selectively enabled in CI.

Remove any ambiguity around whether old or new value is being
returned.

When there is no context for writing output or error messages, use the
default logger.

This includes the output PDF, streams from --show-object and
attachments from --save-attachment. This also enables --verbose and
--progress to work with saving to stdout.

I decided these were confusing and inconsistent with how JSON works.
They muddle the API rather than improving it.

This reverts commit dc059560e73e0b373a6e54e71b07e3af4b692cb4.

I changed my mind. There's no harm in leaving it deprecated for a
release cycle.

See ChangeLog for rationale for not deprecating it as originally
planned.

Remove the name/number tree object helper constructors that don't take
a QPDF&.