OpenSystemsDevelopment / qpdf

 Add new Buffer method copy and deprecate copy constructor / assignment operator

Also fix accidental Buffer copy in Pl_LZWDecoder::addToTable.

 Change JSONHandler::m to std::unique_ptr and declare Members in implementation file

Apply various Clang-Tidy rules

Remove redundant loop in QPDFWriter::prepareFileForWrite

Avoid unnecessary copying of stream dictionary in QPDF::readObject

Manual edits for cases not handled by search and replace

Using search and replace.

If /AP is a dictionary of streams rather than a dictionary of
dictionaries, disregard /AS, which is supposed to point to a subkey of
one of the dictionaries. This fix prevents qpdf's annotation
flattening from discarding some annotations when /AS is erroneously
set.

Add new method QPDF::newReserved()

Add new convenience class QPDFObjGen::Guard