Separate mousewheel-scroll setting & add secondary zoom method

**Is your feature request related to a problem? Please describe.**
Zooming in and out can only be done with the mousewheeel. This can be disrupting to the scroll experience.

**Describe the solution you'd like**
1. Allow user to disable mousewheel zoom without also disabling pinch-to-zoom
2. Provide a secondary method for zooming that doesn't involve the mousewheel, e.g. ctrl-drag

**Describe alternatives you've considered**
n/a

**Additional context**
n/a