fix es6 usage in node-irc

node-irc/node-irc-tests.ts

@@ -1,7 +1,7 @@
 // https://github.com/martynsmith/node-irc/blob/master/example/bot.js
 import irc = require('irc');
 
-let bot = new irc.Client('irc.dollyfish.net.nz', 'nodebot', {
+var bot = new irc.Client('irc.dollyfish.net.nz', 'nodebot', {
     debug: true,
     channels: ['#blah', '#test']
 });

node-irc/node-irc.d.ts

@@ -868,7 +868,7 @@ declare module 'irc' {
          * This contains the set of colors available and a function to wrap
          * text in a color.
          */
-        export const codes: {
+        export var codes: {
             [index: string]: string;
         };
     }