Add level selector and global filters

UI/BigComponents/LevelSelector.svelte

@@ -0,0 +1,29 @@
+<script lang="ts">
+  /**
+   * Shows a 'floorSelector' and maps the selected floor onto a global filter
+   */
+  import LayerState from "../../Logic/State/LayerState";
+  import FloorSelector from "../InputElement/Helpers/FloorSelector.svelte";
+  import { Store, UIEventSource } from "../../Logic/UIEventSource";
+
+  export let layerState: LayerState;
+  export let floors: Store<string[]>;
+  export let zoom: Store<number>;
+  const maxZoom = 16
+
+  let selectedFloor: UIEventSource<string> = new UIEventSource<string>(undefined);
+  
+  selectedFloor.stabilized(5).map(floor => {
+    if(floors.data === undefined || floors.data.length <= 1 || zoom.data < maxZoom){
+      // Only a single floor is visible -> disable the 'level' global filter
+      // OR we might have zoomed out to much ant want to show all
+      layerState.setLevelFilter(undefined)
+    }else{
+      layerState.setLevelFilter(floor)
+    }
+  }, [floors, zoom])
+
+</script>
+{#if $zoom >= maxZoom}
+<FloorSelector {floors} value={selectedFloor} />
+  {/if}