-- pdb2pdbx: fix old style dates (12-SEP-96 -> 12-09-96)
++ pdbx2pdb: process cell parameters
++ pdbx2pdb: process TITLE card
++ pdbx2pdb: process full HEADER information
++ pdbx2pdb: process multiple models
++ pdbx2pdb: correctly process single model
++ pdbx2pdb: !!! Correctly process concatenated files
xx pdbx2pdb: ??? process entities?
++ pdbx2pdb: !!! Wrap arround atom numbers to preserve PDB field widths
xx pdbx2pdb: Print out all fields in the ->asString method (maybe with keywords)
xx pdbx2pdb: Insert TER records into PDB output stream