Add brief pause between receiving and sending messages

-Decreased timeout for messages received with hops_left.

-Added a slight 50 millisecond pause between receiving messages and sending the next message.  This allows a brief moment for duplicate messages to arrive.  I receive a number of duplicate messages with the same hop count.  I believe these are caused by bridging between the powerline and rf signals, apparently this doesn't decrease the hop count.  This slight pause of 50 milliseconds allows the second message to arrive, which as long as the next message has not been sent yet is gracefully ignored.