Best uniprot coverage filter is misleading

Selecting structures by the 'best uniprot coverage' value from the PDBe service is misleading, since that value is calculated with respect to the best matching uniprot sequence, rather than the sequence that Jalview will map to each structure.

Suggest initially, if 'best uniprot coverage is selected' then the filter also:
1. shows the uniprot coverage column.
2. shows the uniprot id for which coverage is for.

Ideally, the filter should aim to select structures where the uniprot ID is the same as the uniprot ID available for the sequence. If none are available, warn the user with a mismatch flag.