Fix firstOnly selection behavior

[jrom99]

firstOnly used to select one match per combination (object+chain+segi), so if one object had multiple chains, each chain would match once.

This makes it so that firstOnly will only match one time per object, on the first segi+chain available (in alphabetical order).

[jrom99]

Another issue I've noticed is that for objects which have residue sequence data available, but the residues don't have structural information (like in loops), this script is unable to find the sequence to select.

But I'm not sure how to update the selection behavior to fix it.

[pslacerda]

I'll check the firstOnly issue soon. Can you dump here some script that check findseq use case?

And about your missing residue issue, I have an idea that seems to work. For sure the sequence data is available in RCSB PDB and mmCIF files but may be missing when they are from other sources, I don't know when it is the case.

The API only cmd.get_fastastr is a command related to findseq, may you see if it works in your case? In my case the FASTA string is retrieved complete but iterate and cmd.get_model aren't, and I don't know why.

https://github.com/schrodinger/pymol-open-source/blob/9d3061ca58d8b69d7dad74a68fc13fe81af0ff8e/modules/pymol/exporting.py#L169

[pslacerda]

The ONE_LETTER table has some errors like the map 'CRF':'TWG' which will ruin the analysis, in case of matching. There are also cases like 'A ':'A', which are not useful.

Edit: I checked some values in ONE_LETTER and I don't trust it.