Add CLI Tool

[fribeiro1]

You may want to consider adding a Command Line Interface (CLI) tool to compile to JS/WASM from the command line. TeaVM is already working on it.

It may help attract the developers of headless apps, in addition to those of web applications.

[Horcrux7]

Please can you give a little more details what you want. Do you want a command line for building/compiling or do you want it at runtime.

A pull request is welcome if you have a specific idea.

[fribeiro1]

Added clarification to the original text.