Implement "badger" kv store back-end for sessions

Former-commit-id: b9d85467238b5611d177b2b95ac9815cf5f8fe83

core/host/world.go

@@ -28,7 +28,7 @@ func RegisterOnInterrupt(cb func()) {
 func notifyInterrupt() {
 	w.mu.Lock()
 	for _, f := range w.onInterrupt {
-		go f()
+		f()
 	}
 	w.mu.Unlock()
 }