Expand the empty shell a bit.

Expand the empty shell a bit.

Add CLI handler on stdin (for now, in production only if
debug is specified).

Implement help, verbos, ping and start.

start forks the child process, sets up listeners on its stdout/stderr
(where nothing should arrive in production).

Add SIGCHLD handler to reap and restart the child.

Add shell "main" for the child:  Set up a CLI handler on the pipes
passed as heritage.

Add ping command and keepalive timeout.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@56 d4fa192b-c00b-0410-8231-f00ffab90ce4