This is a massive rewrite of the help text and cli.rst section of the
manual. All command-line flags now have their own help and are
specifically index. qpdf --help is completely redone.
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.
