Addition of some functions

[dyedd]

1.Add routing group

we can adopt this method.

route::group('admin', [route::any('/index', 'app\admin@index'),
route::any('/settings', 'app\admin@settings')]);

and then you can visit the link such as ‘admin/index’ and ‘admin/settings’

2.Added support for multi-level directory

sometimes，we may work in the multi-level directory instead of root.
therefore，We need the multi-level directory function, if not, set $app to null