Update request context funcs to take concrete types

mux.go

@@ -445,13 +445,13 @@ func CurrentRoute(r *http.Request) *Route {
 	return nil
 }
 
-func requestWithVars(r *http.Request, val interface{}) *http.Request {
+func requestWithVars(r *http.Request, vars map[string]string) *http.Request {
-	ctx := context.WithValue(r.Context(), varsKey, val)
+	ctx := context.WithValue(r.Context(), varsKey, vars)
 	return r.WithContext(ctx)
 }
 
-func requestWithRoute(r *http.Request, val interface{}) *http.Request {
+func requestWithRoute(r *http.Request, route *Route) *http.Request {
-	ctx := context.WithValue(r.Context(), routeKey, val)
+	ctx := context.WithValue(r.Context(), routeKey, route)
 	return r.WithContext(ctx)
 }