Feature request about CardStackListener

[JavierSegoviaCordoba]

Now if I implement this listener, I have a lot of methods that I will not use because I only need one or two.

Should be great to avoid this interface so we can implement the specific methods we want.

[yuyakaido]

@JavierSegoviaCordoba Thank you for proposal! I think this is a good ideal, so I will consider adding this improvement in future version.