Previously, if a listener fails to bind (for example), there was a race in caddy.go between unblocking the startup waitgroup and returning the error and putting it into errChan. Now, an error is returned directly into errChan and the closing of the startup waitgroup is defered until after that return takes place.
Log file can also be stdout or stderr. Log output is disabled by default now, which makes it more feasible to add more log statements to trace program flow in debugging situations.
Fixed bug where manually specifying port 443 disabled TLS (whoops); otherHostHasScheme was the culprit, since it would return true even if it was the same config that had that scheme.
Also, an error at startup (if not a restart) is now fatal, rather than keeping a half-alive zombie server.
By chaining in a middleware handler and using newly exposed hooks from the acme package, we're able to proxy ACME requests on port 443 to the ACME client listening on a different port.
Before, we were activating Let's Encrypt after all the directives were executed. This means their setup functions had access to potentially erroneous information about the server's TLS setup, since the letsencrypt package makes changes to the port, etc. Now, we execute all directives up to and including tls, then activate letsencrypt, then finish with the rest of the directives. It's a bit ugly, but I do think it is more correct. It also fixes some bugs, for example: a host that only has a catch-all redirect.
In testing, I've found that Windows doesn't release the socket right away even though the listener is closed, so calling caddy.Start() right after caddy.Stop() can fail. This change has server.ListenAndServe() try up to 20 times every 100ms to bind the listener, and only return an error if it doesn't succeed after 2 seconds. This might be kind of nifty for Unix, too, but there hasn't been a need for it yet.
The file path of the originally-loaded Caddyfile must be piped to the forked process; previously it was using stdin after the first fork, which wouldn't load the newest Caddyfile from disk, which is the point of SIGUSR1.
