OpenSystemsDevelopment / qpdf

Add details about the new `qpdf::global::inspection_mode` method to the design document, explaining its purpose, functionality, and limitations. Update release notes to highlight its introduction and describe the changes it brings for inspecting and repairing damaged PDF files.

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