Allow %r format to log incomplete records too.
Update docs to reflect new defaults

Fixes #1028

(storage-module facing) bits.

Move the front-side bits to cache.h

Sort #includes according to rules which are for me to know and you
to guess.

bprint macros go in vdef.h,  VCS_* in vcs.h

Remove srandomdev() look-alike, we already have a compat version

Eliminate libvarnish.h embedded #includes.

We now have
	<vapi/vs[mcl].h> for the programmatic API

	<vapi/vs[cl]_int.h> for the underlying structure,
			    shared between API and varnishd