Add reply and application command message types

message.go

@@ -36,6 +36,8 @@ const (
 	MessageTypeChannelFollowAdd
 	MessageTypeGuildDiscoveryDisqualified = iota + 1
 	MessageTypeGuildDiscoveryRequalified
+	MessageTypeReply = iota + 4
+	MessageTypeApplicationCommand
 )
 
 // A Message stores all data related to a specific Discord message.