Generic accessors to query system configuration files.

This is a request for generic accessors to get at the system
congiration files. I can think of one area where we felt that this
would have helped HJ. When users install and run HJ, the very first
time, we check to see if old HJ bookmarks exist and automatically
import it. We extended this and look for netscape bookmarks as well.
On Solaris, we know to look for the .netscape/ under the user's home
directory. Under win32, we have no way to tell where Netscape has been
installed to get at the bookmarks.html file. If JDK could provide
a generic way to get registry information (or the equivalent on the Mac),
it would be a great help.