adds route-spec function to IRouteMatches protocol to return original route

...returns original route as locate-route's third vector value.

I'm proposing this because I need a way to get the original route back from a specific route that has been requested.

It may make sense to further alter locate-route's return value so it returns a hash-map vs. a vector--as it is it's a bit awkward--but I didn't want to go too far with this at this point.

Another thing that may be useful is to return the name of the route if the route is a named route...