req.request is now req.method
vcl_fetch is now vcl_backend_response
error() is now synth()
VCL version number
removed saint mode
new grace logic uses return() - disabled for now
see https://www.varnish-cache.org/docs/trunk/users-guide/vcl-grace.html
"remove" keyword removed, replaced by "unset"
backend errors now handled in vcl_backend_error
removed saint mode
updated redirect: vcl_synth