We now store the parsed site/server block keys with the server block,
rather than parsing the addresses every time we read them.
Also detect conflicting schemes, i.e. TLS and non-TLS cannot be served
from the same server (natively -- modules could be built for it).
Also do not add site subroutes (subroutes generated specifically from
site blocks in the Caddyfile) that are empty.
If a site block has a key like "http://localhost:2016", then the log for
that site must be mapped to "localhost:2016" and not just "localhost"
because "localhost:2016" will be the value of the Host header of requests.
But a key like "localhost:80" does not include the port since the Host
header will not include ":80" because it is a standard port.
Fixes https://caddy.community/t/v2-common-log-format-not-working/7352?u=matt
