Suppose the squares on a chessboard are numbered left to right, top to bottom,
with 0 being the top-left square and 63 being the bottom-right square. Rows are
numbered top to bottom, 0 to 7. Columns are numbered left to right, 0 to 7.
Given a current position on the chessboard, expressed as a row and column
number, calculate the next position on the chessboard, again expressed as a
row and column number. The ordering is determined by the numbering from 0
to 63. The position after 63 is again 0.