Add Go benchmark

[Go](http://golang.org/) qualifies as another benchmark candidate: Goroutines are the equivalent of actors. They become non-blocking when used with buffered channels (though only until the buffer is full). Pattern matching occurs with the switch statement on a value read from a channel:

```
val := <- someChannel
switch val.(type) {
case int: // some code
case float32: // some code
}
```