Cleanups:
-o Clean up introductory comments.
o Log messages should show both original and new size of the data. The speed
should be probably calculated from the former.
o Buffer sizing in shep-export.
Improvements:
o When quicksorting a large input (especially in threaded case), invest more
time to picking a good pivot.
+o Overlay presorter I/O with internal sorting.
Users of lib/sorter/array.h which might use radix-sorting:
indexer/chewer.c