OpenSystemsDevelopment / qpdf

Also, inline method and add optional parameter error_msg.

Now --json-output just changes defaults. Allow output file with --json.

from "qpdf-v2" to "qpdf": [..., ...]

Add additional parameters that will be needed to call QPDF::writeJSON
in partial mode.

Code tidy : replace 0 with nullptr or true

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

Use 'QPDFObjGen const&' instead of 'int, int' in signature.

Use QPDFObjGen::unparse where appropriate.

Also, revert inlining of unparse and operator << from commit 4c6640c in
order to avoid exposing QUtil.

Remove redundant variables pages and next.

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.

Remove variables obsoleted by commit 4f24617.

* Replace --create-from-json=file with --json-input, which causes the
  regular input to be treated as json.
* Eliminate --to-json
* In --json=2, bring back "objects" and eliminate "objectinfo". Stream
  data is never present.
* In --json-output=2, write "qpdf-v2" with "objects" and include
  stream data.

Also add stubs for top-level QPDF methods (createFromJSON,
updateFromJSON)

moddify -> modify. Also carefully spell checked all remaining keys by
splitting them into words and running a spell checker, not just
relying on visual proofreading. That was the only one.

Update getJSON() methods and calls to them