Minor harness fixes, a trace drawer, and an optimal algorithm.

Example runs:
Clear:  opt 11.7  samplerate 10.8  minstrel  8.8
Corner: opt  9.5  samplerate  4.3  minstrel  6.6
Long:   opt  9.9  samplerate  5.4  minstrel  7.0
Moving: opt 11.1  samplerate  9.4  minstrel  9.0