OpenSystemsDevelopment / qpdf

Just because we know an indirect reference is null, doesn't mean we
shouldn't keep it indirect.

Change from unsigned long to int since we pass enumerated type values
to this field.

Full parser context
    Pl_QPDFTokenizer.cc(1): #include ..\..\..\..\src\include\qpdf\Pl_QPDFTokenizer.hh
    Pl_QPDFTokenizer.hh(29): #include ..\..\..\..\src\include\qpdf/QPDFObjectHandle.hh
    QPDFObjectHandle.hh(51): class QPDFObjectHandle
    QPDFObjectHandle.hh(1052): decision to instantiate: PointerHolder<QPDFObject> QPDFObjectHandle::ObjAccessor::getObject(QPDFObjectHandle &)
    --- Resetting parser context for instantiation...
    QPDFObjectHandle.hh(909): parsing: PointerHolder<QPDFObject> QPDFObjectHandle::ObjAccessor::getObject(QPDFObjectHandle &)

Instead of directly putting the contents of the annotation appearance
streams into the page's content stream, add commands to render the
form xobjects directly. This is a more robust way to do it than the
original solution as it works properly with patterns and avoids
problems with resource name clashes between the pages and the form
xobjects.

Wrap an object in an array if it is not already an array.

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.

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.

The QPDF_String::getUTF8Val() method was not treating strings that
weren't explicitly Unicode as PDF Doc Encoded. This only affects
characters in the range 0x80 through 0xa0.

Give objects descriptions and context so it is possible to issue
warnings instead of fatal errors for attempts to access objects of the
wrong type.

As in other cases, this is to enable adding new member variables in
the future without breaking ABI compatibility.

Expose Pl_QPDFTokenizer, and have it do more of the work of managing
the token filter's pipeline.

Implement a TokenFilter class and refactor Pl_QPDFTokenizer to use a
TokenFilter class called ContentNormalizer. Pl_QPDFTokenizer is now a
general filter that passes data through a TokenFilter.

Remove a redundant method that was equal to another one with
additional arguments. This breaks binary compatibility, but there are
other ABI breaking changes in the upcoming release, so now is the time
to do it.

The Apache License version 2.0 is now the primary license for qpdf.
However, users may, at their option, continue to use Artistic version
2.0.

Tweak the message so that we inform the user that we are mitigating
data loss.