OpenSystemsDevelopment / qpdf

Create QPDFJob_options.cc to hold API implementation functions.
Reorganize a little in preparation for moving public member variables
private and creating the real QPDFJob API that will be used by callers
as well as the argv/json initialization methods.

The previous commits have removed all references to memory from
QPDFArgParser from QPDFJob. This commit removes the constraint that
QPDFArgParser remain in scope. This is a prerequisite to allowing JSON
as an alternative way to initialize QPDFJob and to initialize it
directly using a public API.

Also fix QPDFArgParser

Replace most of the calls to QUtil::copy_string with this instead.

Handle optional choices in addition to required choices. Refactor the
way help options are added to completion to make it work with optional
help choices.

Move ArgParser from qpdf.cc into QPDFJob.cc. It still works with
millions of public member variables, but now qpdf.cc is minimal and
just calls stable library functions.

Convert remaining static functions that take QPDFJob& as a parameter
to member functions. Utility functions that don't take QPDFJob& remain
static functions and can probably just stay that way since the keep
extra complexity out of QPDFJob.hh.

Remove remaining temporary duplication of hard-coded values and direct
access to std::cout, std::cerr, and whoami in favor of parameters in
QPDFJob. This moves a few more static methods into QPDFJob member
functions.

Remove all calls to exit() from QPDFJob. Handle code that runs in
verbose mode to enable it to make use of output streams and message
prefix (whoami) from QPDFJob. This removes temporarily duplicated exit
code logic and most access to whoami/std::cout outside of QPDFJob
proper.

Move most of the methods called from qpdf.cc after argument parsing
into QPDFJob. In this increment, enough QPDFJob API has been added to
handle the branch of QPDFJob::run() that creates output with an
appropriate division between qpdf.cc and QPDFJob.

There are temporary bits of code to enable everything to compile and
pass the test suite, including some duplication and hard-coded values.

Commit by ejb@ql.org using m-holger as author so git annotate gives
proper credit for changes.

Add methods isNameAndEquals, isDictionaryOfType, isStreamOfType

They have to be ot_* rather than qpdf_ot_* for compatibility.

* Different enumerated types are not assignment-compatible in C++, at
  least with strict compiler settings
* While you can do `constexpr ot_xyz = ::qpdf_ot_xyz` in QPDFObject.hh to
  make QPDFObject::ot_xyz work, QPDFObject::object_type_e::ot_xyz will
  only work if the enumerated type names are the same.