Invoked via a standard Digester CallMethodRule, passing the
"body text" of the top-level xml element. This demonstrates
the default behaviour of Digester (which is not suitable for
processing markup-style xml).
Main method of this test harness. Set up some digester rules,
then parse the input xml contained in the "in" member variable.
The rules cause methods on this object to be invoked, which just
dump information to standard output, to show the callbacks that
a real program could arrange to get when parsing markup input.