Fix build (#76)

Track Varnish 7.1.x

Bump varnish version

Update to 7.0.1

Correct case insensitive match

Reduce diff with 6.0

Sync with upstream changes

Rearrange headers to fix some warnings

Switch to VSB_new_auto and VSB_destroy for now

Sync code with github.com/varnish/varnish-modules

Add missing $Event for the event function, ops!

Switch to vmod_priv_methods

Update signatures

Switch to WS_ReserveAll

vtree.h is include in Varnish now