Moved GenVector to common dir
Problem: function to return a big amount (one million --> one billion) of unique random numbers,
                having only getRandom() which returns 0 <= n <=1

Solution: implement Durstenfeld solution:
To shuffle an array a of n elements (indices 0..n-1):
  for i from n − 1 downto 1 do
       j ← random integer with 0 ≤ j ≤ i
       exchange a[j] and a[i]