switching to composition API

src/components/MainMenu.vue

@@ -7,20 +7,11 @@
   </div>
 </template>
 
-<script>
+<script setup>
   import MenuCellProperties from "./MenuCellProperties.vue";
   import MenuGeneralOptions from "./MenuGeneralOptions.vue";
   import MenuElementaryCA from "./MenuElementaryCA.vue";
   import Menu2dCA from "./Menu2dCA.vue";
-  export default {
-    name: "MainMenu",
-    components: {
-      MenuCellProperties,
-      MenuGeneralOptions,
-      MenuElementaryCA,
-      Menu2dCA,
-    },
-  };
 </script>
 
 <style>