CoffeeScript REPL should be able to require coffeescript files.

lib/coffee-script/repl.js

@@ -145,6 +145,7 @@
         console.warn("Node 0.8.0+ required for CoffeeScript REPL");
         process.exit(1);
       }
+      require('./extensions');
       opts = merge(replDefaults, opts);
       repl = nodeREPL.start(opts);
       repl.on('exit', function() {