reorganize code a bit : debug code going to debug.js, put packets reading code in a function, add types using a addTypes function

src/debug.js

@@ -0,0 +1,17 @@
+var util = require('util')
+
+var debug;
+if (process.env.NODE_DEBUG && /(minecraft-protocol|mc-proto)/.test(process.env.NODE_DEBUG)) {
+    var pid = process.pid;
+    debug = function(x) {
+        // if console is not set up yet, then skip this.
+        if (!console.error)
+            return;
+        console.error('MC-PROTO: %d', pid,
+            util.format.apply(util, arguments).slice(0, 500));
+    };
+} else {
+    debug = function() { };
+}
+
+module.exports = debug;