Module refactor - almost CommonJS compatible now

API change summary:

  * require("/sys.js") becomes require("sys")

  * require("circle.js") becomes require("./circle")

  * process.path.join() becomes require("path").join()

bin/node-repl

@@ -1,11 +1,11 @@
 #!/usr/bin/env node
 
-process.mixin(require("/utils.js"));
+process.mixin(require('sys'));
 puts("Welcome to the Node.js REPL.");
 puts("Enter ECMAScript at the prompt.");
 puts("Tip 1: Use 'rlwrap node-repl' for a better interface");
 puts("Tip 2: Type Control-D to exit.");
 
-require("/repl.js").start();
+require('repl').start();
 
 // vim:ft=javascript