When a QPDF is destroyed, changing indirect objects to direct nulls
makes them effectively disappear silently when they sneak into other
places. Instead, we should treat this as an error. Adding a destroyed
object type makes this possible.
This is in preparation for restoring a QPDFObject.hh to ease the
transition on qpdf_object_type_e.
This commit was created by
* Renaming QPDFObject.cc and QPDFObject.hh
* Replacing QPDFObject\b with QPDFValueProxy (where \b is word
boundary)
* Running format-code
* Manually resorting files in libqpdf/CMakeLists.txt
* Manually refilling the comment in QPDF.hh near class Resolver
Allow QPDFObjectHandle::obj to be set prior resolving object.
ot_unresolved has been appended to the list object types in order to
preserve the output of existing test cases.
* Change DLL_EXPORT to libqpdf_EXPORTS (internal to the build). The
new name is cmake's default, is more conventional, and is less
likely to clash with other symbols.
* Add QPDF_DLL_PRIVATE for non-Windows
* Make logic around when to define QPDF_DLL et al more explicit
* Add detailed comments
