fv - calculate 'magical square'
What is it?
Find 'magical squares'.
From wikipedia: "In recreational mathematics, a magic square of order n is an arrangement of nē numbers, usually distinct integers, in a square, such that the n numbers in all rows, all columns, and both diagonals sum to the same constant. A normal magic square contains the integers from 1 to nē. The term "magic square" is also sometimes used to refer to any of various types of word square.".
0.2: added diagonals check
0.1: initial release