OpenSystemsDevelopment / qpdf

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.

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.

Turns out you can keep adding zero to a number over and over again and
it just doesn't get any bigger. Who would have known?

During periods of intensive operation on a specific file, this method
can reduce the overhead of repeated open/close operations.

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

If we are unable to filter a page's content streams, don't attempt to
remove objects from the page's resource dictionary. Also provide a
command line option to suppress resource removal in case we ever need
this as a workaround for some bug or broken PDF files.

If parsing content streams is treated as a warning, there is no way
for a caller to know if a parsing operation has failed. This is very
dangerous and will likely result in data loss when token filters are
parser callbacks are in use.

It's not really a shallow copy. It just doesn't cross indirect object
boundaries. The old implementation had a bug that would cause multiple
shallow copies of the same object to share memory, which was not the
intention.

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.

Provide a convenient way of accessing rectangles.

The special case around name token was not reachable. This would only
affect constructors of name tokens that were represented in
non-canonical form such as with a hex substitution for a printable
character. The error was harmless but still a bug.

This fixes CVE-2018-9918.

Remove calls to assertPageObject(). All cases in the library that
called assertPageObject() work fine if you don't call
assertPageObject() because nothing assumes anything that was being
checked by that call. Removing the calls enables more files to be
successfully processed.

Prior to this fix, if there was a loop detected in following /Prev
pointers in xref streams/tables, it would cause qpdf to lose data.
Note that this condition causes many PDF readers to hang or fail.

This is for testing the release process, particularly as it pertains
to AppImage creation.