fix difficulty menu raycastability updates

src/components/difficulty-background.js

@@ -0,0 +1,17 @@
+/**
+ * Handle difficulty raycastability.
+ * Needed since state component does not have a bind-toggle that works within a bind-for.
+ */
+AFRAME.registerComponent('difficulty-background', {
+  schema: {
+    enabled: {type: false}
+  },
+
+  update: function () {
+    if (this.data.enabled) {
+      this.el.setAttribute('raycastable', '');
+    } else {
+      this.el.removeAttribute('raycastable');
+    }
+  }
+});