Given a N by M matrix of numbers, print out the matrix in a clockwise spiral.
For example, given the following matrix:
[[1, 2, 3, 4, 5], [6, 7, 8, 9, 10], [11, 12, 13, 14, 15], [16, 17, 18, 19, 20]]
You should print out the following:
1 2 3 4 5 10 15 20 19 18 17 16 11 6 7 8 9 14 13 12