New port: irc/weechat-otr

WeeChat script for Off-the-Record (OTR) Messaging. This script makes every
effort to securely provide OTR Messaging in WeeChat

Submitted by: Vinícius Zavam <egypcio@googlemail.com>
Sponsored by: Rubicon Communications, LLC (Netgate)
Differential Revision: https://reviews.freebsd.org/D16327