2D Array-hourglassSum
///An hourglass in A is a subset of values with indices falling in this pattern in ARR's graphical representation:
a b c
d
e f g
///Example
-9 -9 -9 1 1 1
0 -9 0 4 3 2
-9 -9 -9 1 2 3
0 0 8 6 6 0
0 0 0 -2 0 0
0 0 1 2 4 0
The hourglass sums are:
-63, -34, -9, 12,
-10, 0, 28, 23,
-27, -11, -2, 10,
9, 17, 25, 18