Add Vuex position and timestamp getters for real-time event

lib/www/client/source/src/store/modules/notify/getters.js

@@ -32,4 +32,19 @@ function point (state) {
   return Number(v) || v;
 }
 
-export default { serverEvent, online, lineName, sequence, line, point };
+function position (state) {
+  const λ = Number(_(state, "serverEvent.payload.new.meta.longitude"));
+  const φ = Number(_(state, "serverEvent.payload.new.meta.latitude"));
+
+  if (!isNaN(λ) && !isNaN(φ)) {
+    return [ λ, φ ];
+  }
+  return null;
+}
+
+function timestamp (state) {
+  const v = _(state, "serverEvent.payload.new.meta.time");
+  return v;
+}
+
+export default { serverEvent, online, lineName, sequence, line, point, position, timestamp };