error has been long retired.

Mark optional parts as such and briefly document components. Sync with
the man page. The address part for options -a and -b is technically
optional too.

We should perhaps rename this parameter away from sigsegv_handler?
Maybe error_sighandler? Maybe move it into a feature bit for the
disabling instead of a separate parameter too.

This allows for a panic dump and backtrace to be produced on
sigabrt. This is useful e.g. when using jemalloc's debug flags, which
can through a special environment variable enable memory allocation
consistency checks and trigger sigabrt on errors.

Reported and diff submitted by Gauthier Delacroix on varnish-dev.

Makes this work with multiple instances under systemd.
Discussed with ingvar on irc.

Fixes startup if vcl_dir was specified in DAEMON_OPTS.
Reported by Gauthier Delacroix. Discussed with ssm on irc.

Fixes #1765

understand them.

Fixes: #1770

For continuous updates we can always use a shell loop.

Fixes #1760.

Please note that using underscore in HTTP headers is considered a
really bad idea because many application frameworks map minus to
underscore in environment variables.

Fixes: 	#1768

Discussed with Martin.

Add commas to panic line endinges consistently

This dumps some useful bits about the state of the client connection.

If s_indent > 0 and the buffer is empty, it would check s_buf[-1] for
the '\n' character.

Now it will indent either on previous character being a newline, or on
empty buffer. This allows indenting also the very first line of a
buffer.

Based largely on patch from:	Martin

I wonder if we should make the panic output (readable) JSON format ?

Submitted by:	fgs

"2eq" instead of "Req" didn't look right.