expose mafft --large to support large alignments

[nbokulich]

Improvement Description
Usually mafft step aligning seqs depletes RAM and the job stops. mafft --large option has a possibility to circumvent this problem, by saving tmp data into files instead of using RAM.

This will enable use of this plugin for aligning longer reads, e.g., from oxford nanopore. Currently the longer reads cause memory to explode.

Current Behavior
No --large option

Proposed Behavior
Expose --large

References
Quoting forum xref