Mouse wheel event callback

Hi Alvaro,

Saw this [website](https://sharp.vn/vn/cong-nghe-long-giat-khong-lo/), and I would like to know the trick how we can achieve this kind of function with `fullpage.js`. Or can you prepare this as one of your extension because it seems like can be useful for everyone in future.

The main thing is, when scroll, animation will trigger until the last scroll of the animation. And when the animation is finished, another scroll will lead to next section. (maybe need to set delay timing on `onleave` function, but I'm not so sure with this one)

From my understanding, it need to concentrate on `scroll` function, but I not master in javascript code.

Any advice for this issue will be appreciated.

Thanks.