Com: Append new line when flusing serial

Our HID implementation sends fixed-length reports, that will be parsed
by the receiving software.
Serial outputs are more geared towards debugging, thus splitting the
messages sent is much more usable.

src/Com.cpp

@@ -20,6 +20,7 @@ namespace Com {
 		usb_rawhid_send(buffer, 0);
 #else
 		Serial.write((const char*)buffer);
+		Serial.write('\n');
 #endif
 		/* Clear the buffer. */
 		memset(buffer, 0, sizeof(buffer));