Change the protocol stack processing to pass packets by non-const

reference, rather than const reference and value as was previously done.
Also change  the queue semantics to return the packet on a deque, rather
than requiring a packet as a parameter.  The problem with the original
approach was that packet UID's were getting skipped.  The fix handles
the uid properly, and we get sequential packet uid's on the trace file.

src/node/node.cc

@@ -213,7 +213,7 @@ Node::UnregisterProtocolHandler (ProtocolHandler handler)
 }
 
 bool
-Node::ReceiveFromDevice (Ptr<NetDevice> device, const Packet &packet, 
+Node::ReceiveFromDevice (Ptr<NetDevice> device, Packet &packet, 
                          uint16_t protocol, const Address &from)
 {
   bool found = false;