inchilib: invoke user callbacks on clean stack
test: add passing test for round-trip of caffeine
test: add failing test for round-trip of fructose
inchi: use whole atom object, not just elname
inchilib: ensure memory allocated by NanCString is freed
inchilib: support stereo0D
inchilib: retain all atom information, not just name
test: update tests, add cholesterol
inchilib: support for stereo data