Start the long awaited overhaul of the backend code and syntax.

Start the long awaited overhaul of the backend code and syntax.

Off the bat, this affects only the simple backend case, and the
main thrust is a syntax change from a dynamic procedural assignment
style:

	backend b1 {
		set backend.host = "fs.freebsd.dk";
		set backend..port = "80";
	}

to a constant structural definition style:

	backend b1 {
		.host = "fs.freebsd.dk";
		.port = "80";
	}

A helpfull compile error will advice on this change.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@2356 d4fa192b-c00b-0410-8231-f00ffab90ce4