Pretty print, using recursion (tables) and colors.

I've modified the main print function to use recursion (expand tables, to a certain point), and colors. I find this very useful (it behave pretty much like the built-in print of Node.js). One caveat: there's no tty detection for now, so the color characters are always on. Before we merge this into the master, does anyone know how to detect whether io.stdout support colors or not?