Allow adjusting zoom speed

[nNoidea]

Allow us to zoom in slower or faster by changing the speed through the settings.

I feel like the current zoom in speed is too slow, but some people might also find it fast or perfect. So a customizable setting would be great!

Also, it's an amazing and clean extension <3!

[ArgonAlex]

There also might be a kind of bug here too. I noticed that when I use my scrollwheel with one slower+longer continous scroll, it zooms noticably faster than using mutiple rapid+shorter scrolls. This feels counterintuitive.