OpenSystemsDevelopment / qpdf

Avoid calling finish() multiple times on the pipeline passed to
pipeContentStreams. This commit also fixes a bug in which qpdf was not
exiting with the proper exit status if warnings found while splitting
pages; this was exposed by a test case that changed.

Make some more methods in QPDFPageObjectHelper work with form
XObjects, provide forEach methods to walk through nested form
XObjects, possibly recursively. This should make it easier to work
with form XObjects from user code.

Also removes preclusion of stream references in stream parameters of
filterable streams and reduces write times by about 8% by eliminating
an extra traversal of the objects.

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

This reverts an incorrect fix to #449 and codes it properly. The real
problem was that we were looking at the local dictionaries rather than
the foreign dictionaries when saving the foreign stream data. In the
case of direct objects, these happened to be the same, but in the case
of indirect objects, the object references could be pointing anywhere
since object numbers don't match up between the old and new files.

The test suite now contains test cases that fail with both 10.0.1 and
10.0.2 and reproduce the internal error from #449.

Warnings issued on the output QPDF object were not suppressing
warnings since that option was only set on the input QPDF object.

* Return rather than exiting from realmain in qpdf.cc
* Remove extraneous blank line
* Don't assign temporary to const reference

Specifically, if a stream had its stream data replaced and had
indirect /Filter or /DecodeParms, it would result in non-silent loss
of data and/or internal error.

Wildcard expansion is different in Windows from non-Windows and
sometimes requires special link options to work. Add tests that fail
if we link incorrectly.

Use autoconf rather than ifdefs to determine what format string to use
for long long.

Make clear that you almost always want + or - before an angle when
specifying rotation.

When possible, use `for (auto&` or `for (auto const&` when iterating
using C++-11 style iterators.

Also switch to colon-style iteration in some cases. Thanks to Dean
Scarff for drawing this to my attention after detecting some
unnecessary copies with
https://clang.llvm.org/extra/clang-tidy/checks/performance-for-range-copy.html