[Qexo-general] improved base-uri and document functions

[Per Bothner]

I checked in enhancements to the base-uri and document
functions so they now more-or-less follow the spec:
* When you run an XQuery program on the command line
(without compiling it first), the base-uri is set
to the url of the program.
* When you KawaPageServlet, it also sets the base-uri.
* If you specify a relative url as the only argument
to document, it uses the value of base-uri().

This makes it easy to refer to resource using relative
URLs.  I've implemented a quick-and-dirty method to resolve
a URL relative to a base URI.  It would have been nice to use
java.net.URI, but that's a JDK1.4-only feature, so I wanted
to avoid that.  Please let me know how it works.  I'm
especially interested in how it works under Windows.
--
        --Per Bothner
address@hidden   http://www.bothner.com/per/