Improve the VCL compiler in various ways:

Improve the VCL compiler in various ways:

Generate the methods and their legal returns with the tcl script.

Add consistency checks to make sure methods don't use illegal returns,
and also check called subrourtines.

Add consistency check to complain about recursive subroutine calls.

Add consistency check to complain about unused or undefined subroutines.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@222 d4fa192b-c00b-0410-8231-f00ffab90ce4