add 'backspace' to InteractiveChoices

[qwiglydee]

To clear clozeand to see initial placeholder.

[Fabioriz]

Hello my friend! How are you doing? I don't know exactly what this space is for, but I added your collections into my Anki and it is really amazing! Congratulations on having created such amazing cards!
When using your cards, I've realized something: how much I misspell words! =( It's amazingly time consuming the amount of times that I type incorrectly. And the natural key I use to correct is backspace. Is there a way to enable this key to work in cloze cards? Thank you in advance! Regards! Fábio