A more idiomatic way of trying a non-blocking send on a buffered channel

and falling back to a blocking send inside a goroutine.

This really needs to be fixed. The situation only arises when events are
sent and aren't pulled off the channel using {Wait,Poll}ForEvent.
Namely, if the event send blocks, the entire program will deadlock.

Using a goroutine is not ideal because we lose a guarantee of order:
that events are processed in the order of their arrival. However, it
seems OK as a temporary band-aide for a situation that probably doesn't
arise too often.

What I need to do is implement a dynamic queue. Here is a reference
implementation: http://play.golang.org/p/AiHBsxTFpj

nexgb/xgb.go

@@ -379,12 +379,14 @@ func (c *Conn) readResponses() {
 			// FIXME: I'm not sure if using a goroutine here to guarantee
 			// a non-blocking send is the right way to go. I should implement
 			// a proper dynamic queue.
-			if cap(c.eventChan) == len(c.eventChan) {
+			// I am pretty sure this also loses a guarantee of events being
+			// processed in order of being received.
+			select {
+			case c.eventChan <- event:
+			default:
 				go func() {
 					c.eventChan <- event
 				}()
-			} else {
-				c.eventChan <- event
 			}
 
 			// No more processing for events.