OpenSystemsDevelopment / qpdf

Avoid calling getAllPagesInternal for each /Page object.

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

Over time, qpdf's grade has dropped on lgtm, but they are not
transparent about how grades are assigned. Fixing current alerts, in
my opinion, reduces clarity and maintainability of the code in the
name of performance in non-critical sections of code. Some analysis by
m-holger suggests that fixing some of the current alerts actually
degrades performance (slightly) while fixing others results in
insignificant improvements. The quality of qpdf can be measured in
other ways, such as its extensive test suite, documentation, and long
track record of reliably manipulating PDFs with high performance, few
bugs, and few external dependencies. The lgtm rating is a distraction
at best.

When the schema wants a variable-length array, allow a single item as
well as allowing an array.

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

Tidy QPDFObjGen related code

Also, change test for QPDFObjGen::isIndirect to obj != 0.
Delete comment from commit afd35f9.

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

Use QPDFObjGen::unparse where appropriate.

Change method signatures to use QPDFObjGen.
Replace QPDF_Stream::objid and generation with QPDF_Stream::og.

Change method signatures to use QPDFObjGen.
Use QPDFObjGen methods where possible.
Remove redundant QPDF::objGenToIndirect.

Change method signature to use QPDFObjGen.

Change method signature to use QPDFObjGen.

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

Rather than using object id -1 to mean "don't care", use object ID 0,
and clarify the difference between that use and indication of a direct
object.

ABI breaking change