Treat a DMRD packet as a silent keepalive

This is because the other end may not have enabled ENHANCED_OBP,
DMRD is traffic so the server is up, and not sending to systems
we can receive from can cause weird effects on the network.

hblink.py

@@ -220,6 +220,9 @@ class OPENBRIDGE(DatagramProtocol):
 
                 # Userland actions -- typically this is the function you subclass for an application
                 self.dmrd_received(_peer_id, _rf_src, _dst_id, _seq, _slot, _call_type, _frame_type, _dtype_vseq, _stream_id, _data)
+                #Silently treat a DMRD packet like a keepalive - this is because it's traffic and the 
+                #Other end may not have enabled ENAHNCED_OBP
+                self._config['_bcka'] = time()
             else:
                 h,p = _sockaddr
                 logger.info('(%s) OpenBridge HMAC failed, packet discarded - OPCODE: %s DATA: %s HMAC LENGTH: %s HMAC: %s SRC IP: %s SRC PORT: %s', self._system, _packet[:4], repr(_packet[:53]), len(_packet[53:]), repr(_packet[53:]),h,p)