OpenSystemsDevelopment / qpdf

Also switch URLs for the qpdf and qtest websites to sourceforge.io
(https) instead of sourceforge.net (http).

Also handle direct annotation, though this is much less likely.

If not found in the field hierarchy, /Q and /DA are supposed to be
looked up in the document-level form dictionary. /DR is supposed to
only come from the document dictionary.

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.

This takes pages from the file in groups of n with default = 1. This
partially fixes the enhancement in issue #505 but doesn't implement
the entire suggestion.

Also fix a bug in checking consistency of length for stream data
providers. Length should not be checked or recorded if the provider
says it failed to generate the data.

For now, --allow-insecure allows creation of files with the owner
passwords empty or matching the user password.

When removing unreferenced resources, notice if a page (recursively)
contains a form XObject with unreferenced resources, and count any
such resources as referenced by the page.