Shutdown network transport (#153)

Shutdown socket before close. Some OS:es seem to not wake up the reading thread on close, but will do so on shutdown. So add a workaround.

RFXtrx/__init__.py

@@ -963,6 +963,7 @@ def reset(self):
     def close(self):
         """ close connection to rfxtrx device """
         with suppress(socket.error):
+            self.sock.shutdown(socket.SHUT_RDWR)
             self.sock.close()