OpenSystemsDevelopment / qpdf

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

Since Buffer has always implemented its copy constructor with a deep
copy, its Members object will never have multiple owners. Change to unique_ptr.

Also implement move constructors for Buffer, since there may be cases
where a deep copy is not needed.

On destruction of the QPDF object replace all indirect object references
with direct nulls.

Remove all existing code to release resolved references.

Fixes performance issue due to interaction of resetting QPDFValue::qpdf and
og members and prior code.

This doesn't need an explicit destructor anymore.

Now that QPDFObject.hh is out of the public API, we don't really need
QPDFObjAccessor. Also, the function didn't have to be virtual anymore.

We don't put specific copyright banners on files that aren't installed.

This required moving some newly inlined functions back to the cc file,
but that seems to have had no measurable performance impact.

Avd xcsv brvtns.

Tidy QPDF::getAllPagesInternal and QPDF::pushInheritedAttributesToPageInternal

Also, modify QPDFObject::swapWith to update the ObjGens of the swapped
objects.

Modify QPDF::newIndirect and QPDF::updateCache to keep object ObjGens
up to date.

Modify QPDFParser::parse to call QPDF::getObject instead.

Add a new obj_cache entry or update an existing entry in place.

Also change QPDF::replaceObject and QPDF::swapObjects such that the
QPDFObject assigned to an og in the obj_cache is never replaced; only
QPDFObject::value is updated.

Centralise casting of QPDFObjects and reduce repeated dereferencing.

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.

Report mem usage

Also remove no-longer-needed #include