[new] devel/lua-argparse version 0.7.1

Hi,

I would like to import a new port for devel/lua-argparse, a simple Lua
module for command line parser inspired by argparse for Python.

GH repository https://github.com/luarocks/argparse

I need this Lua module to update devel/luacheck and after discussions
with jsg@, he advised me to create this new port.

This port supports FLAVORS for Lua 5.1, 5.2, 5.3 and 5.4.

Install and tests OK on amd64.

Comments welcome and please commit if OK.

Laurent