Enable user configuration setting/overriding with dot arguments

[insin]

E.g. if you want to use a different Babel stage preset...

--babel.stage=0

...or try Webpack 3's new scope hoisting…

--webpack.hoisting

…or strip development only code but keep output readable for debugging…

--no-webpack.uglify.mangle --webpack.uglify.beautify

…etc. etc. without needing a config file or having to update your config file.