tractshredder works in a similar way to shredder, but processes streamlines instead
of scalar data. The input is raw streamlines, in the format produced by track or
procstreamlines.
The program first makes an initial offset of offset tracts. It then reads and
outputs a group of bunchsize tracts, skips space tracts, and repeats until
there is no more input.
EXAMPLES
Output every third streamline from the file tracts.Bfloat.