[Request] When closing a channel ask for the PIN to confirm the operation

[tosdan]

When creating a new channel it asks for the PIN (at least when I have the option "Ask for PIN before payment" enabled). I think it would make people feel much safer if it would ask for the PIN for closing a channel as well. Actually, I wouldn't mind if it would ask even for some further confirmation like "Are you really sure?" even when it's a mutual close.