OpenSystemsDevelopment / qpdf

Ensure copied annotations are fixed (fixes #600)

 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

Case where pages from a main input without /AcroForm key were duplicated
was omitted

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.