Exercise 2.52: Make changes to the square limit
of wave shown in Figure 2.9 by working at each of the levels
described above.  In particular:


 Add some segments to the primitive wave painter of Exercise 2.49
(to add a smile, for example).

 Change the pattern constructed by corner-split (for example, by using
only one copy of the up-split and right-split images instead of
two).

 Modify the version of 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.)