Fix I2C config parameter interpretation

[zfields]

The current implementation pulls bytes out of the sysex buffer, regardless of whether or not the user specified such bytes.

[fpistm]

Access to argv[1] before test argc is risked? no ?

if (argc > 1) {
      delayTime = (argv[0] + (argv[1] << 7));
      if (delayTime > 0) {
        i2cReadDelayTime = delayTime;
      }
}

[zafields]

In this circumstance, there is no risk, because argv is a statically allocated buffer:

arduino/Firmata.h

Line 114 in e0592e7

uint8_t parserBuffer[MAX_DATA_BYTES];

You can see it being supplied to the callback:

arduino/FirmataParser.cpp

Line 455 in e0592e7

(*currentSysexCallback)(currentSysexCallbackContext, dataBuffer[0], sysexBytesRead - 1, dataBuffer + 1);

You are right, in saying it would be best practice to do so, and to protect against the buffering scheme being changed. For now I want a surgical fix, before I implement a much broader change to the firmware.

[rwaldron]

This change would need to be made across all variants.

[soundanalogous]

lgtm!