Optimize the ShiftRows(), InvShiftRows() and RotWord() functions

Optimize the ShiftRows(), InvShiftRows() and RotWord() functions

This switches from using self-defined circular_left_shift() and
circular_right_shift() functions to do rotation of a word to using
shifts. This is a measurable amount faster than making all of the copies
that were being made before.

Note that this can get better, I just need to figure out how to get back a
word from a byteArray.

Signed-off-by: Ira W. Snyder <devel@irasnyder.com>