Enhance Links for SPA

Replace the init function of the Router object with:

init: () => {
    document.querySelectorAll("a.navlink").forEach(a => {
        a.addEventListener("click", event => {
            event.preventDefault();
            const href = event.target.getAttribute("href");
            Router.go(href);
        });
    });  
    // Process initial URL   
    Router.go(location.pathname);
},