New test %sort. This takes a sorted list, picks 1% of the list positions

New test %sort.  This takes a sorted list, picks 1% of the list positions
at random, and replaces the elements at those positions with new random
values.  I was pleasantly surprised by how fast this goes!  It's hard to
conceive of an algorithm that could special-case for this effectively.
Plus it's exactly what happens if a burst of gamma rays corrupts your
sorted database on disk <wink>.

 i    2**i  *sort  ...  %sort
15   32768   0.18  ...   0.03
16   65536   0.24  ...   0.04
17  131072   0.53  ...   0.08
18  262144   1.17  ...   0.16
19  524288   2.56  ...   0.35
20 1048576   5.54  ...   0.77