Flush the serial buffers after opening the port.

Sometimes there are garbage bytes present after opening the serial
port, which causes the communication to fail. Flushing the buffers
after a small delay is all it takes to get rid of those bytes.

src/cressi_leonardo.c

@@ -131,6 +131,9 @@ cressi_leonardo_device_open (dc_device_t **out, dc_context_t *context, const cha
 		return DC_STATUS_IO;
 	}
 
+	serial_sleep (device->port, 100);
+	serial_flush (device->port, SERIAL_QUEUE_BOTH);
+
 	*out = (dc_device_t *) device;
 
 	return DC_STATUS_SUCCESS;