FIX: Format numbers a tad better

I still think there is some way to go, but this is closer to Excel

base/src/test/test_number_format.rs

@@ -8,6 +8,15 @@ fn test_simple_format() {
     assert_eq!(formatted.text, "2.3".to_string());
 }
 
+#[test]
+fn test_maximum_zeros() {
+    let formatted = format_number(1.0 / 3.0, "#,##0.0000000000000000000", "en");
+    assert_eq!(formatted.text, "0.3333333333333330000".to_string());
+
+    let formatted = format_number(1234.0 + 1.0 / 3.0, "#,##0.0000000000000000000", "en");
+    assert_eq!(formatted.text, "1,234.3333333333300000000".to_string());
+}
+
 #[test]
 #[ignore = "not yet implemented"]
 fn test_wrong_locale() {