Fix one line in distance metric
Fix one line in distance metric

The "universal distance metric" had a bug in one line that had never come up.  If the two objects being compared have a shape, but the shapes are not the same, then it tried to take the supnorm between them; this fails because arithmetic is not defined on tuples.  Fix simply converts the shape tuples into arrays.

econ-ark/HARK,econ-ark/HARK