Update plyvisitor.h
Update plyvisitor.h

Signed-off-by: spotenza2016 <cc7dec814d856f4990a080d5efa6998443b69b71@users.noreply.github.com>
OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs