OpenSystemsDevelopment / qpdf

Use "QPDF" only for the QPDF class itself.

Remove paragraph about traversal during destruction since this is still necessary with the
new implementation.

QPDFValueProxy wasn't a good name for it. We decided the evil of
having the header file be named QPDFObject_private.hh was less than
the evil of having the class be named something other than what it
should have been named.

Some people don't know what CI is, so remove use of that abbreviation
when it doesn't add any value.

* Don't surprise people with deprecation warnings
* Provide detailed instructions and support for the transition