Support the CIF/mmCIF file format.

[danny305]

I am familiarizing myself with this repository(release 3.4) and see that in the function read_molecule_file raises a value error if the suffix of the file is not explicitly .pdb.

My research group is in the middle of moving all of our code infrastructure over to the CIF file format since the pdb file format is deprecated.

I have requested this to the authors of some of our dependencies (pdb2pqr, freesasa) last year.

I am wondering if there are any plans to move propka3 to the cif file format?

[sobolevnrm]

We've been slowly working up to CIF support for PDB2PQR and other codes so I think this is feasible in the not-too-distant future.

[dargen3]

Any update on this, please?