This makes quark's vhost-handling very powerful while still being
simple.
Imagine you have a website with a subdomain you really want
to move back to your main domain.
Say the subdomain is called "old.example.org" and you want to serve it
under "example.org" but in the subdirectory "old/", i.e. you want to
redirect a request "old.example.org/subdir/" to "example.org/old/subdir".
For a vhost-handler that only takes 4 arguments for each vhost this is
actually pretty powerful.
This ensures that quark really does not care if the incoming connection
is plain HTTP or relayed TLS-traffic from a proxy or tunnel. Depending
on the previous negotiation, the client will make the right decision on
which scheme to use in a given context.
And many other things, too many to list here. For example, it now
properly logs uds instead of erroring out.
Separating concerns in many places definitely improves the readability.
