slice2html creates broken links for nested modules

Thanks so much for the slice2html tool! It's much more convenient than slice2docbook for creating quick API documentation.

One bug: it seems to create broken links when there is more than one level of module nesting. I was able to reproduce this with a fairly simple test case. Create the following Slice file and run slice2html on it:

module test {
    module sub1 {
        interface Test1 {
            void method1();
        };
    };
};

The proper directory structure is created and most of the links work. However, if you open test/sub1.html, it's got "Up" and "Previous" links that both point to "test.html", which doesn't exist; as far as I can tell, the correct link would be "../test.html".

MEF