Syntax enhancement and CLI for node.js.

Hi! I read your reddit post and I made some commits to it to show my support.

The changes include:

+ Adding `var` before variable assignment done with `def`
+ Adding a frequently used `let*` as a syntax that compiles to familiar JavaScript idiom.
+ A simple command-line interface that runs on node.js

Have a nice day:)

p.s. I suggest you write some tests