Refactoring: move all code files into a src directory

src/UI/InputElement/Validators/LengthValidator.ts

@@ -0,0 +1,16 @@
+import { Validator } from "../Validator"
+
+export default class LengthValidator extends Validator {
+    constructor() {
+        super(
+            "distance",
+            'A geographical distance in meters (rounded at two points). Will give an extra minimap with a measurement tool. Arguments: [ zoomlevel, preferredBackgroundMapType (comma separated) ], e.g. `["21", "map,photo"]',
+            "decimal"
+        )
+    }
+
+    isValid = (str) => {
+        const t = Number(str)
+        return !isNaN(t)
+    }
+}