OpenSystemsDevelopment / qpdf

Since the files autogen.sh creates are now controlled, you only have
to run autogen.sh when you modify the source files, not when you
build from a clean checkout.

to avoid line ending problems

Update documentation to reflect that automatically generated files are
committed. Detect when they are outdated if we have the ability to
regenerate them.

libtool make install already works this way.

Use free Azure Pipelines to do Linux, Windows, and Mac build and test
and to generate Windows binary distributions.

This creates a zip file of the files that are present in a source
distribution but not present in the repository.

Some files in the test suite trigger antivirus warnings. These are
not infected files with malicious intent. They are test files to
ensure that qpdf does not crash when it encounters the files. This
change enables those files to be obfuscated in the source repository
so that checking out qpdf from version control or extracting the
source code doesn't trigger antivirus warnings.

This fix allows qpdf to compile/test cleanly with gcc 8.

Rather than keeping a list of buffers for every write, accumulate
bytes in a single buffer, doubling the size of the buffer when needed
to accommodate new data.

This is not the best possible implementation, but the change was
implemented in this way to avoid changing the shape of Pl_Buffer and
thus breaking backward compatibility.

Reported in debian bug 902642

A previous fix introduced a potentially memory overrun under certain
rare conditions. The test suite now once again passes with address
sanitizer.

There were a few places in the code that were checking that a pointer
wasn't null before deleting it, even though C++ has always allowed
delete 0. Most of the code did not perform these checks.

CR, CRLF, and LF are all supposed to be treated as LF; only one EOL is
to be ignored after backslash.