[jdom-interest] Push toward a 1.0 API

[Jason Hunter]

> The root-cause methods in JDOMException match the ones in JDK 1.4, but we
> don't use the base implementation at all, because then we'd be dependent on
> 1.4. That's fine. 

Perfect.

> - The printStackTrace() methods should automatically pick up JDK 1.4 nested
> exceptions, since the 1.4 spec says that Throwable.printStackTrace() will
> print the nested stack trace too. So even though our getNestedException()
> doesn't know about 1.4 nested exceptions, this should work fine.

Good.

> - On the other hand, the 1.4 spec does not say that getMessage() will
> recurse to nested exceptions. So our getMessage() method will stop when it
> hits a 1.4 nested exception. In this case we could consider checking for 1.4
> nested exceptions (via reflection), and appending their messages. On the
> other hand, it is a little disturbing that our getMessage() method recurses
> while the 1.4 one doesn't. IIRC, I added this because the error messages
> were extremely unhelpful and frustrating, because the real error was hidden.
> So I wouldn't want to change this. Not sure what the right solution is here.

I like the message recursion and wouldn't want to give it up.  I don't
think we need to change the behavior of exception classes outside our
control though, so leaving it alone is probably best.

I'll cross this off the TODO.  Thanks!

-jh-