remove demo game

scene.trigger.go

@@ -0,0 +1,10 @@
+package pncdsl
+
+// Trigger fires Do when its When condition first becomes true after the
+// trigger arms (on scene enter). One-shot per scene visit by default.
+type Trigger struct {
+	Name string
+	When Condition
+	Do   Action
+	Once bool
+}