Refactoring: move all code files into a src directory

src/UI/Base/MapControlButton.svelte

@@ -0,0 +1,17 @@
+<script lang="ts">
+  import { createEventDispatcher } from "svelte"
+  import { twJoin } from "tailwind-merge"
+
+  /**
+   * A round button with an icon and possible a small text, which hovers above the map
+   */
+  const dispatch = createEventDispatcher()
+  export let cls = ""
+</script>
+
+<button
+  on:click={(e) => dispatch("click", e)}
+  class={twJoin("pointer-events-auto m-0.5 h-fit w-fit rounded-full p-0.5 sm:p-1 md:m-1", cls)}
+>
+  <slot />
+</button>