Add a token type "METHOD", we use it for reference counting.

Add a token type "METHOD", we use it for reference counting.

Add a reference to the first backend {} we encounter, it is the default.
Add a reference to all backends assigned explicitly.
Add a reference to all methods.

Enable reference check, complain if: backend, function or acl is defined
but not used, or used but not defined.

git-svn-id: svn+ssh://projects.linpro.no/svn/varnish/trunk@227 d4fa192b-c00b-0410-8231-f00ffab90ce4