Add LAST search option

[kullrich]

Dear David Emms,

next to BLAST+, DIAMOND and MMSEQS2,

LAST (https://gitlab.com/mcfrith/last) is another protein search alternative.

It is known, that in comparison to diamond or mmseqs2 it lacks sensitivity but gains speed (see e.g.: https://github.com/soedinglab/mmseqs2/wiki).

I have altered the config.json file and added last citation accordingly. Maybe you could add it in a future release.

Best regards Kristian Ullrich