Add way to hook into auto-reconnect and cancel it

Closes #171
Fixes #170

client.go

@@ -59,6 +59,9 @@ type Client struct {
 	EnableAutoReconnect   bool
 	LastSuccessfulConnect time.Time
 	AutoReconnectErrors   int
+	// AutoReconnectHook is called when auto-reconnection fails. If the function returns false,
+	// the client will not attempt to reconnect. The number of retries can be read from AutoReconnectErrors.
+	AutoReconnectHook func(error) bool
 
 	sendActiveReceipts uint32
 
@@ -380,6 +383,10 @@ func (cli *Client) autoReconnect() {
 			return
 		} else if err != nil {
 			cli.Log.Errorf("Error reconnecting after autoreconnect sleep: %v", err)
+			if cli.AutoReconnectHook != nil && !cli.AutoReconnectHook(err) {
+				cli.Log.Debugf("AutoReconnectHook returned false, not reconnecting")
+				return
+			}
 		} else {
 			return
 		}