OpenSystemsDevelopment / qpdf

Move responsibility for creating shared pointers to objects and cloning from QPDFObjectHandle to QPDFObject.

Update getJSON() methods and calls to them

Add virtual methods to QPDFObject, wrappers to QPDFObjectHandle, and
implementations to all the QPDF_Object types.

QPDFObjectHandle::{new,is,assert}Reserved, QPDF::replaceReserved
provide a mechanism to add objects to a PDF file when there are
circular references.  This is a prerequisite to copying objects from
one PDF to another.