The GNU diff algorithm translated to a Java class. The Diff class computes
the differences between two Object arrays as a list of changes. This is
very general purpose. Any of the options to GNU diff can be efficiently
implemented as variations on how Object.equals() is implemented and how the
change list is printed. DiffPrint now sports a setOutput() method. The
DiffPrint.Base class and derivatives should really be renamed out of the
empty package.
