OpenSystemsDevelopment / qpdf

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.

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.

Create a computationally and memory efficient implementation of name
and number trees that does binary searches as intended by the data
structure rather than loading into a map, which can use a great deal
of memory and can be very slow.

Refactor QPDF_Stream to use stream filter classes to handle supported
stream filters as well.

Fixes qpdf/qpdf#417

Thanks to Zdenek Dohnal <zdohnal@redhat.com> for contributing the code
used for the gnutls crypto provider.

ClosedFileInputSource is an input source that keeps the file closed
when not reading it.

This is the beginning of higher-level API support using helper
classes. The goal is to be able to add more helpers without continuing
to pollute QPDF's and QPDFObjectHandle's public interfaces.

Implement a TokenFilter class and refactor Pl_QPDFTokenizer to use a
TokenFilter class called ContentNormalizer. Pl_QPDFTokenizer is now a
general filter that passes data through a TokenFilter.

Additional testing is added in later commits to be supported by
additional changes in the library.

Rather than checking consistency of libqpdf.map, generate it.

The build now checks to make sure libqpdf.map has the right library
version number in it.

Also update maintainer documentation on binary compatibility testing.