fix all core script syntax issues

examples/nat_client.ce

@@ -8,15 +8,17 @@ $contact((actor, reason) => {
     log.console(reason)
   }
 }, {
-  address: "108.210.60.32",  // NAT server's public IP
+  address: "108.210.60.32",
   port: 4000,
   actor: $self
 })
 
-$receiver(e => {
-  switch(e.type) {
-    case 'greet':
-      log.console(`hello!`)
-      break
+var handlers = {
+  greet: function() {
+    log.console(`hello!`)
   }
+}
+
+$receiver(e => {
+  if (handlers[e.type]) handlers[e.type]()
 })