Explicitly abandon removal of unreferenced resources if there are any
lexical errors in the page's contents. This case always generated a
warning, but it now also prevents removal of unreferenced resources,
this strongly decreasing the likelihood of data loss.
When removing unreferenced resources, the code was copying the overall
resource dictionaries but not the subdictionaries being modified. This
was a "typo" in the code -- the comment clearly stated the need to do
this, but the code replaced the dictionary with itself rather than
with a shallow copy of itself.
If set, we avoid using Windows I/O HANDLE, which is disallowed in some
versions of the Windows SDK, such as for Windows phones.
QUtil::same_file will always return false in this case. Only applies
to Windows builds.
The original QPDF is only required now when the source
QPDFObjectHandle is a stream that gets its stream data from a
QPDFObjectHandle::StreamDataProvider.
Some of the images were supposed to have no filter, but somewhere
along the line, they ended up with /FlateDecode, most likely because
qpdf rewrote the file without having --compress-streams=n specified.
If this error is repeated, it will cause a test failure.
Instead of calling assert for problems found during checking
linearization data, throw an exception which is later caught and
issued as an error. Ideally we would handle errors more robustly, but
this is still a significant improvement.
On certain operations, such as iterating through all objects and
adding new indirect objects, walk through the entire object structure
and explicitly resolve any indirect references to non-existent
objects. That prevents new objects from springing into existence and
causing the previously dangling references to point to them.
