Make the test window bigger in Java.
Some test utility improvement/refactoring.
New builder-based Net API.

This allows one to add request headers, read response headers, and (except on
platforms that won't support it like HTML and maybe Flash) access the response
payload in its binary form.

Also added a NetTest for testing GETs, POSTs, &c.

The new deal is currently only implemented on Java, but the other platforms are
forthcoming.