OnStartup and OnShutdown callbacks now run as part of restarts, too.
The startup and shutdown directives only run their commands NOT as part
of restarts, as before. Some middleware that use OnStartup may need to
switch to OnFirstStartup and implement OnFinalShutdown to do any cleanup
as needed.
- Server types no longer need to store their own contexts; they are
stored on the caddy.Instance, which means each context will be
properly GC'ed when the instance is stopped. Server types should use
type assertions to convert from caddy.Context to their concrete
context type when they need to use it.
- Pass the entire context into httpserver.GetConfig instead of only the
Key field.
- caddy.NewTestController now requires a server type string so it can
create a controller with the proper concrete context associated with
that server type.
Tests still need more attention so that we can test the proper creation
of startup functions, etc.
