Change minimum step size for integers to 1.
Change minimum step size for integers to 1.

If we don't do this, then the stencil utilization may be *very* inefficient
for small step sizes, because many trial steps will round to the same integers.

Perhaps we could be aggressive and choose a smaller minimum, such as 0.5,
but 1 seems like a safe choice.

eriknw/dask-patternsearch