If a chain ID is missing / invalid, skip (to read non-standrd PDB)
If a chain ID is missing / invalid, skip (to read non-standrd PDB)

Also add support for reading CRYST1 records

Signed-off-by: Geoff Hutchison <9cf35bacc9f8512ca007341c9e919cf5dc03e0c7@gmail.com>

ghutchis/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,OpenChemistry/avogadrolibs,ghutchis/avogadrolibs,OpenChemistry/avogadrolibs