Fixes:	#1746

It used to be possible to specify -sfile size in percentage. This
feature has been removed. Update the users guide to reflect this.

Fixes: #1744

Fixes #1745

shutuppery about indentation.

order.

Use it to health poke backends, rather than wasting a thread per
backend+poll.

for a very long time and never been shown to actually improve performance.

These days we pick busyobj out of a memory pool which gives us much better
control of the amount of memory sitting idle waiting to become a busyobj.

In case a single mempool not scale well enough, we make a mempool per
thread pool to scale horizontally.

config we have in Jenkins.

See comment XXX questions to discuss with phk

varnishd will (try to) to accept on the default port *:80 and listen to cli
commands.

A warning will get emitted:

Warning: Neither -b nor -f given, won't start a worker child.
         Master process started, use varnishadm to control it.

Some systems cannot resolve service "http", so in commit
8c7e459d we changed the
hardcoded default service from "http" to "80".

Before we complicate the implementation uselessly to first look
up http and then fall back to 80, just docfix. Port 80 is probably
_the_ one assignment with the least chance of ever changing.

the pool waiter for the working thread doing the recycling.

This does not restrict which threads can reuse the connection later on.

but retain stats stuff (since it runs across pools) in cache_pool.c