tabular CLI output proof of concept hack

[Dridi Boukelmoune]

> But I am also seriously wondering if we should go even further and
> have varnishd *only* produce JSON output, and leave the render-for-humans
> aspect to varnishapi or even varnishadm.

Ideally implement it in libvarnish.a and expose it in libvarnishapi,
with a way for varnishadm to specify a window size in interactive
mode. This way varnishd -d will be able to produce the plain text
output.

Dridi