Scrolling on touch pad triggers slide changing multiple times

[DaKoala]

I usually use touch pad to browse websites. I noticed that if I use touch pad to move between slides, a slight scrolling will trigger slide changing multiple times.
I am currently on macOS 10.14.3 and my laptop is Macbook Pro.
The same problem also appears on a PC with Windows 10 as long as scrolling with a touch pad.

[DaKoala]

I have already come up with a solution using throttling function. PR #564