Update I2C_READ_CONTINUOUSLY to match I2C_READ w/ no provided slaveRegister

By "testing" did you run the unit tests? I don't think there is a unit test for this yet. Or did you mean by running the code and you got the expected results? I would think without the int type that a byte set to -1 would be either 0 or 255 (I forget exactly since I hardly ever write c code anymore).