parse PDB / mmCIF header/medata to improve autodetection of models, licensing and cross-references

Jalview should be able to autodetect AlphafoldDB structures imported directly since they include text like the following in the TITLE and REMARK lines:

HEADER 01-JUN-22
TITLE ALPHAFOLD MONOMER V2.0 PREDICTION FOR TRIOSEPHOSPHATE ISOMERASE
..
Licensing can be obtained from the REMARK:
REMARK 1 ACADEMIC AND COMMERCIAL PURPOSES, UNDER CC-BY 4.0 LICENCE.
Finally, 'UNP' refers to the Uniprot accession:
DBREF XXXX A 1 253 UNP A0Q8C4 TPIS_FRATN 1 253

So importing a pdb file like this should yield a sequence annotated with temperature factor interpreted as PLDDT automatically, and a database cross-reference to uniprot with the stated accession.