Implement a facility for source file modularization in the VCL

Implement a facility for source file modularization in the VCL
compiler.  The syntax is:

	include "filename" ;

Unlike the C preprocessors #include directive, a VCL include can
appear anywhere in the sourcefile:

	if {req.Cookie == include "cookie.vcl" ; || !req.Host } {
	}

and have cookie.vcl contain just:

	"8435398475983275293759843"

Technically this results in a change to how we account for source
code references in the counter/profile table as well, and as a result
the entire source code of the VCL program is now compiled into the
shared library for easy reference.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@1281 d4fa192b-c00b-0410-8231-f00ffab90ce4