OpenSystemsDevelopment / qpdf

* Merge overloaded functions by adding default values
* Remove non-const methods that are identical to const methods

(patrepl and cleanpatch are my own utilities)

patrepl s/PointerHolder/std::shared_ptr/g {include,libqpdf}/qpdf/*.hh
patrepl s/PointerHolder/std::shared_ptr/g libqpdf/*.cc
patrepl s/make_pointer_holder/std::make_shared/g libqpdf/*.cc
patrepl s/make_array_pointer_holder/QUtil::make_shared_array/g libqpdf/*.cc
patrepl s,qpdf/std::shared_ptr,qpdf/PointerHolder, **/*.cc **/*.hh
git restore include/qpdf/PointerHolder.hh
cleanpatch
./format-code

Run this:

for i in  **/*.cc **/*.c **/*.h **/*.hh; do
  clang-format < $i >| $i.new && mv $i.new $i
done

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.

None of these are in the public API.

This was originally not public because I wanted to get rid fo the
pages cache, but I recently realized there were deep reasons not to do
that, and the author of pikepdf wanted this, so I decided to make it
public.

This results in a performance penalty of 1% to 2% when replaceObject
and swapObjects are never called and a somewhat larger penalty if they
are called, but it's worth it to avoid very confusing behavior as
discussed in depth in qpdf#507.

I thought /EFF was supposed to be used as a default for decrypting
embedded file streams, but actually it's supposed to be advice to a
conforming writer about handling new ones. This makes sense since the
findAttachmentStreams code, which is not actually needed, was never
right.

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

StreamDataProvider::provideStreamData now has a rich enough API for it
to effectively proxy to pipeStreamData.

This also reverts the addition of a new checkLinearization that
distinguishes errors from warnings. There's no practical distinction
between what was considered an error and what was considered a
warning.

This makes all integer type conversions that have potential data loss
explicit with calls that do range checks and raise an exception. After
this commit, qpdf builds with no warnings when -Wsign-conversion
-Wconversion is used with gcc or clang or when -W3 -Wd4800 is used
with MSVC. This significantly reduces the likelihood of potential
crashes from bogus integer values.

There are some parts of the code that take int when they should take
size_t or an offset. Such places would make qpdf not support files
with more than 2^31 of something that usually wouldn't be so large. In
the event that such a file shows up and is valid, at least qpdf would
raise an error in the right spot so the issue could be legitimately
addressed rather than failing in some weird way because of a silent
overflow condition.

Full parser context
    QPDF.cc(2): #include ..\..\..\..\src\include\qpdf\QPDF.hh
    QPDF.hh(48): class QPDF
    QPDF.hh(1380): decision to instantiate:  QPDF::ResolveRecorder::ResolveRecorder(QPDF *,const QPDFObjGen &)
    --- Resetting parser context for instantiation...
    QPDF.hh(799): parsing:  QPDF::ResolveRecorder::ResolveRecorder(QPDF *,const QPDFObjGen &)

Full parser context
    QPDF.cc(2): #include ..\..\..\..\src\include\qpdf\QPDF.hh
    QPDF.hh(47): class QPDF