`Serial.flush()` Outdated

[santaimpersonator]

Several customer have reported that the Serial.flush() function no longer clears the input and output buffers; it only clears the output buffer.

The firmware needs to be updated for this change:
https://github.com/sparkfun/OBD-II_UART/blob/master/Firmware/obdIIUartQuickstart.ino#L55
https://github.com/sparkfun/OBD-II_UART/blob/master/Firmware/obdIIUartQuickstart.ino#L60
https://github.com/sparkfun/OBD-II_UART/blob/master/Firmware/obdIIUartQuickstart.ino#L83

A common recomendation from the Arduino forum:

while(Serial.available() > 0) {
  char dump_buf = Serial.read();
}