Feature: add slope measurement input

src/UI/InputElement/Validators/SlopeValidator.ts

@@ -0,0 +1,13 @@
+import NatValidator from "./NatValidator"
+
+export default class SlopeValidator extends NatValidator {
+    constructor() {
+        super("slope", "Validates that the slope is a valid number")
+    }
+    isValid(str: string): boolean {
+        if (str.endsWith("%") || str.endsWith("°")) {
+            str = str.substring(0, str.length - 1)
+        }
+        return super.isValid(str)
+    }
+}