Improve how REPL commands are evaled

Before:
> {a: 1}
1
> (function() {
...   // foo
...   return 1;
... })();
...

Now:
> {a: 1}
{ a : 1 }
> (function() {
...   // foo
...   return 1;
... })();
1
>

lib/repl.js

@@ -104,12 +104,12 @@ function REPLServer(prompt, stream) {
     if (!skipCatchall) {
       // The catchall for errors
       try {
-        self.buffered_cmd += cmd;
+        self.buffered_cmd += '\n' + cmd;
         // This try is for determining if the command is complete, or should
         // continue onto the next line.
         try {
           // Use evalcx to supply the global context
-          var ret = evalcx(self.buffered_cmd, context, 'repl');
+          var ret = evalcx('(' + self.buffered_cmd + ')', context, 'repl');
           if (ret !== undefined) {
             context._ = ret;
             self.stream.write(exports.writer(ret) + '\n');