Change the CLI protocol in a subtle but useful way:

Change the CLI protocol in a subtle but useful way:

The first line of the response has a fixed format ("%-3d %-8u\n")
and consequently fixed length (CLI_LINE0_LEN == 13).

This makes parsing responses more efficient.  Add a function
in common_cli to do so.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@630 d4fa192b-c00b-0410-8231-f00ffab90ce4