CifWriter.ciffile() is changed to CifWriter.cif_file() in pymatgen

[yutaoki]

ciffile() method is now changed to cif_file() method in pymatgen.io.cif.CifWriter.

The lines using ciffile() should be changed to cif_file() in core.py.

[yutaoki]

Also, .maxlen attribute should be changed to .max_len in core.py

[kousuke-nakano]

Dear @yutaoki, thank you for the report! Yes, SHRY supports an old version of pymatgen. Would you let us know the version you used?