This introduces a `Delayed` type in `RoutingApplication.hs` that
contains a handler together with delayed checks. There are several
blocks of delayed checks, so that we can ultimately execute them in the
order we desire.
The process is documented in more detail in `RoutingApplication.hs`.
The main `Server.Internal` module was getting a bit large for my taste.
It now contains just the instances. All the administrative utilities
are in their own dedicated modules.
