OpenSystemsDevelopment / qpdf

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

There are codepoints in PDFDoc that are not valid UTF-8 but map to
valid UTF-8. We were handling those correctly with bidirectional
mapping.

However, if those same code points appeared in UTF-8, where they have
no meaning, they were left as fixed points when converting to PDFDoc,
where they do have meaning. This change recognizes them as errors.

Convert loops to use range-based for statements.
Simplify the extract_bookmarks function.

Remove test for type == /XObject in QPDFObjectHandle::isFormXObject
as type value is optional (as per spec 8.10.2).

Replace code to test for /Form in QPDFJob::shouldRemoveUnreferencedResources
with a call to isFormXObject.

Sometimes someone may build only a subset of the documentation. The
logic has to be conditional upon whether it exists, not whether it is
built, since we pull pre-built docs in for CI installation.

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 is to catch pull requests that make changes that would affect
automatically generated job files without including those
modifications.

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.

Clarify that names are to appear in canonical form with PDF escaping
resolved when used in non-parsing QPDFObjectHandle APIs and their C
API counterparts. See https://github.com/qpdf/qpdf/discussions/625.

This will be able to be replaced with QUtil::make_shared_array

Replace PointerHolder arrays wherever it can be done without breaking ABI.

* Don't surprise people with deprecation warnings
* Provide detailed instructions and support for the transition

Change "-" to "--" for named parameters.
Remove spaces inside "[ option ]" for optional parameters.
Fix "pdf-mod-info --dump file" to match usage message.