Before this commit:
1. you could not edit a menu URL because the input was hidden.
This was due to radio options being switched (new page is now selected choice)
when you create a menu.
But when you edit, there is no choice and the input should be shown.
2. if you set a menu url to an email address, the display link would be prefixed
by a / and so it would open mysite.com/mailto:XXX instead of just the mailto
Now:
1. Input is now hidden only when you add a new menu, not when editing a menu.
2. mailto link now works as expected: it will open your desktop mail software