Previously it said `vcl_all' which doesn't exist.  Minor cosmetics while
I'm here.

Partially addresses #1795.

This was missing on my previous commit.

Disabled by default. Prompted by Rafael Zalamena
(rafaelfz at taghos dot com dot br) on varnish-dev.

From minusf via github with minor tweaks.

For those cases where you want to send a different reason
message, but use the normal status code.

Noticed by Kacper when doing 301/302 in vcl_synth().

A very minor spelling fix for something I noticed whilst reading the source
for CIDR notation inside ACLs.

understood.

Until I get a burst of inspiration, let's not release a blatant TODO in
the  docs.

Better ordering of the topics, and hopefully better wording overall.

This is to not leak the size of struct object to stevedores that might
have their own cache_obj.c implementation.

Minor fixes for FreeBSD by:	phk

From Carlos Abalde (carlos-dot-abalde-at-gmail-dot-com) with comments
from Dridi and phk.