Ludus CLI (v0.1.0)

The Ludus CLI has five modes: `help`, `version`, `run`, `listen`, and `send`.

* `help`: Output this text and exit.

* `version`: Ouput the current version number.

* `run`: Runs a Ludus script: `ludus run {script}`.

* `listen`: Starts a Ludus "listener" server, which receives Ludus source code on a given port and outputs the results. Similar to a REPL, intended to be used in conjunction with `send`, from a text editor.

* `send`: Sends text from `stdin` to a listening server. Any text editor that can send highlighted text to a command line program can evaluate Ludus source.