I don't know if you're accepting feature requests but there is one thing I think is missing. That would be multiple choice questions. The same as the radio buttons but with checkboxes.
Currently there is something in there called checkbox but it only allows you to have one checkbox. I guess that would only be used for something like "I have read and agree to the terms and conditions."
I would attempt to modify the code myself and add those in there but I'll probably mess something up.