Add radio input option in prompt dialogs as requested on issue #189 using @CrankyDragon code.
Add radio input prompt dialogs
A group of radiobutton inputs should only yield one value. I don't see that you're handling that correctly.
The tests at 1504 and 1517 don't entirely make sense, as you don't need to "uncheck" a radio button - checking another radio in the group causes the uncheck on it's own.
This basically looks like a simple clone of the checkbox code with minor updates. @makeusabrew?