get rid of Interaction

it's no longer needed in the closure-based actor method scheme

router/utils.go

@@ -10,11 +10,6 @@ import (
 	"net"
 )
 
-type Interaction struct {
-	code       int
-	resultChan chan<- interface{}
-}
-
 func checkFatal(e error) {
 	if e != nil {
 		log.Fatal(e)