XML_Node, and made them public.
It turns out the Cabinet.h routines needed these. Previously, they
were using the compiler default routines, which was a bug.
Now, they are using explicit routines. Note, these new routines
have not been checked. However, they do have the chance of being
correct.
Declared the XML_Node copy constructor and assignment operators
to be private -> they don't work, so accidently invoking them is
an error. Now, a compilation error will occur.
Note, the copy() routine can be used instead to create copies
of XML trees.
