UPDATE: Adds web app (#79)

Things missing:

* Browse mode
* Front end tests
* Storybook

webapp/src/components/formatUtil.ts

@@ -0,0 +1,36 @@
+export function increaseDecimalPlaces(numberFormat: string): string {
+  // FIXME: Should it be done in the Rust? How should it work?
+  // Increase decimal places for existing numbers with decimals
+  const newNumberFormat = numberFormat.replace(/\.0/g, ".00");
+  // If no decimal places declared, add 0.0
+  if (!newNumberFormat.includes(".")) {
+    if (newNumberFormat.includes("0")) {
+      return newNumberFormat.replace(/0/g, "0.0");
+    }
+    if (newNumberFormat.includes("#")) {
+      return newNumberFormat.replace(/#([^#,]|$)/g, "0.0$1");
+    }
+    return "0.0";
+  }
+  return newNumberFormat;
+}
+
+export function decreaseDecimalPlaces(numberFormat: string): string {
+  // FIXME: Should it be done in the Rust? How should it work?
+  // Decrease decimal places for existing numbers with decimals
+  let newNumberFormat = numberFormat.replace(/\.0/g, ".");
+  // Fix leftover dots
+  newNumberFormat = newNumberFormat.replace(/0\.([^0]|$)/, "0$1");
+  return newNumberFormat;
+}
+
+export enum NumberFormats {
+  AUTO = "general",
+  CURRENCY_EUR = '"€"#,##0.00',
+  CURRENCY_USD = '"$"#,##0.00',
+  CURRENCY_GBP = '"£"#,##0.00',
+  DATE_SHORT = 'dd"/"mm"/"yyyy',
+  DATE_LONG = 'dddd"," mmmm dd"," yyyy',
+  PERCENTAGE = "0.00%",
+  NUMBER = "#,##0.00",
+}