This should resolve #56 (and #1053 in Umbraco Forms).

This issue was the rendering of multiple, identical messages for required checkbox or radio button lists - with the PR in place we now only have one per fieldset:

I've done this will two extra checks in rendering the summary bullet points:

• If adding a message for a checkbox or radio button which may be "invalid" even though it's actually valid due to another item with the same input name being checked, check that the field itself is invalid before adding a message.
• Not added if an identical message has already been added.

I also fixed up an issue found in testing this along with a previous update, which was that in these cases where we add or remove an error from other inputs with the same name, we weren't updating the cached this.summary value for all inputs. This caused the summary to not render sometimes as it was considered unchanged.

To test this you should be able to look at the "Checkboxes" demo which I've updated to include a radio button list too, as well as a validation summary element.