Function seed::routing::initial

pub fn initial<Ms, Mdl>(
    app: App<Ms, Mdl>, 
    routes: fn(_: &Url) -> Ms
) -> App<Ms, Mdl> where
    Ms: Clone + 'static,
    Mdl: Clone + 'static, 

For setting up landing page routing. Unlike normal routing, we can't rely on the popstate state, so must go off path, hash, and search directly.