add some example routes to routes.php; add reveal method to get $app.
use the reveal method.
Session to accept session storage in case for testing.
test basic app functionality; from request to get response with text.
trial on UrlGenerator and tests.
moved UrlGenerator to Http
add an argument to __invoke, as quick to method.
set UrlGenerator as a service in App, register it to template engine, and use it.
not to save responder in $request; access it via App::reveal method.
reformat code.
refactored to pass a new request for invoke app, and rewrite information of the existing request when responded.
request is also another service; reformat some code.