New port: deskutils/ladon

Process many files in parallel. It is meant for people comfortable
with using a terminal but strives to be as easy to use as humanly
possible.

Ladon is named after the multiheaded serpent dragon from Greek mythology,
slain by Heracles and thrust into the sky as the constellation Draco. His
many heads allow you to efficiently work on many files at once.

WWW: https://github.com/danielgtaylor/ladon

PR: 201906
Submitted by: Carlos Jacobo Puga Medina <cpm@fbsd.es>