Fix for changing arguments with serial communication methods.

[markrages]

Don't mutate argument, even with odd lengths.

Test case:

import u3

lj = u3.openAllU3().popitem()[1]

data = [1]

lj.i2c(0x10,data)

assert data == [1]

(I see that u6.py and ue9.py have the same problem, but I don't have hardware to test those.)

[davelopez01]

Thanks for catching and fixing. I pulled in the changes and will look into fixing the same issues for the U6 and UE9.