Make changes to the square limit of wave by working at each of the
levels of abstraction. In particular:
wave painter of
Exercise 2.49
(to add a smile for example).corner-split (for example, by
using only one copy of the up-split and right-split images
instead of two).square-limit that uses square-of-four so
as to assemble the corners in a different pattern. (For example,
you might make the big Mr. Rogers look outward from each corner of
the square.)TODO