caddy.go:569: could be simplified

sigtrap_posix.go:87: value of inst is never used

upgrade.go:151: should omit nil check; len() for nil slices is defined as zero

Changes the log output of on startup

* Handle the case of an OCSP responder certificate expiring before an OCSP response it issued

* oops

* doh, gofmt

A default of true is risky when protecting assets by matching base path.
It's not obvious that protecting /foo/ will allow /Foo/ through, and if
accessing static files on a case-insensitive file system... that's no
good. So the default is now to be case-INsensitive when matching paths.

Provides a new hook for plugins as a means to provide the current caddy.Instance when starting or restarting.

* Implement 'command' plugin

* Rename 'command' to 'on'

* Split this PR

This allows you to have multiple redir directives conditioned solely
upon if statements, without regard to path.

I am not a lawyer, but according to the appendix of the license,
these boilerplate notices should be included with every source file.

When two Caddyfiles with the same name, but different paths, are
imported, it can cause a weird bug because isNewLine() returned false
when it should return true, since the files are actually different,
but it couldn't know that because only the base name was stored,
not the whole path.

Signed-off-by: Tw <tw19881113@gmail.com>

Fix pid error in linux sysvinit

Create /var/log/caddy.log and chown prior to starting caddy.
Caddy running as DAEMONUSER does not have permission to create the /var/log/caddy.log.

This change eliminates the `[ERROR] Could not write pidfile: open /var/run/caddy.pid: permission denied` from caddy.log.
The start-stop-daemon writes the file as root so the DAEMONUSER that caddy runs as cannot write to the .pid file.

This reverts commit 56453e96.

Benchmarks with wrk showed no noticeable performance impact