further progress towards json port

ipaacalib/cpp/include/ipaaca/ipaaca-buffers.h

ipaacalib/cpp/include/ipaaca/ipaaca-definitions.h

ipaacalib/cpp/include/ipaaca/ipaaca-forwards.h

ipaacalib/cpp/include/ipaaca/ipaaca-internal.h

ipaacalib/cpp/include/ipaaca/ipaaca-ius.h

ipaacalib/cpp/include/ipaaca/ipaaca-payload.h

ipaacalib/cpp/include/ipaaca/ipaaca.h

ipaacalib/cpp/src/ipaaca-buffers.cc

ipaacalib/cpp/src/ipaaca-internal.cc

ipaacalib/cpp/src/ipaaca-ius.cc

ipaacalib/cpp/src/ipaaca-json.cc

ipaacalib/cpp/src/ipaaca-payload.cc