OpenSystemsDevelopment / qpdf

Run compare images tests when QPDF_TEST_COMPARE_IMAGES is set rather
than when QPDF_SKIP_TEST_COMPARE_IMAGES is not set.

This is so it will fit on one line after a qtest upgrade allows us to
split lines.

The PDF spec only allows UTF-16BE, but most readers seem to accept
UTF-16LE as well, so now qpdf does too.

This was unintended behavior that was added back for backward
compatibility. It is intentionally undocumented.

If we're opening a PDF file to copy its encryption information or
attachments, its version doesn't need to influence the output version.

This comment expands all tabs using an 8-character tab-width. You
should ignore this commit when using git blame or use git blame -w.

In the early days, I used to use tabs where possible for indentation,
since emacs did this automatically. In recent years, I have switched
to only using spaces, which means qpdf source code has been a mixture
of spaces and tabs. I have avoided cleaning this up because of not
wanting gratuitous whitespaces change to cloud the output of git
blame, but I changed my mind after discussing with users who view qpdf
source code in editors/IDEs that have other tab widths by default and
in light of the fact that I am planning to start applying automatic
code formatting soon.

Use get() and use_count() instead. Add #define
NO_POINTERHOLDER_DEPRECATION to remove deprecation markers for these
only.

This commit also removes all deprecated PointerHolder API calls from
qpdf's code except in PointerHolder's test suite, which must continue
to test the deprecated APIs.

add qpdf_oh_new_binary_unicode_string and qpdf_oh_get_binary_utf8_value

Let argv be a null-terminated array. There is already code that
assumes this, and it makes it easier to construct the arguments.

This makes it much more convention to use the initializeFromArgv
functions since you can use string literals.

All the coverage cases that used to be in qpdf.cc are now in
QPDFJob*.cc. It doesn't really matter, but better to follow the
convention of starting with the class that includes the coverage call.

Changing from bool requiring true to string requiring the empty string
is more consistent with the CLI and makes it possible to add an
optional parameter or choices later without breaking compatibility.

Flatten everything to make it easier to map command-line flags to
json. The old structure was an illusion anyway because there was no
mechanism to enforce that things were in the right place. This also
helps with future flexibility.

Use "file" consistently for specifying a file path. We use "filename"
when adding attachments for a completely different purpose.