Weirdly enough, the "simple-scopes" test doesn't return undefined
anymore, at first I thought the scoping was somehow broken, turns out
the interpreter doesn't consider the returned y as the last evaluated
value anymore, possibly because it's undefined (?).
Now that we have the beginnings of a parser, let's take the script to
run as a command-line argument and move all the test scripts into
/home/anon/js :^)
To run a script, simply use "js":
$ js my-script.js
To get an AST dump before execution, you can use "js -A"
