Add new port: devel/onscripter and devel/onscripter-1byte

PR: 196654
Differential Revision: https://reviews.freebsd.org/D1800
Approved by: bapt (mentor)

Open source clone of NScripter, a game engine used to create and
perform visual novels.

WWW: http://onscripter.sourceforge.jp/onscripter.html