Scroll zooms out in web interface

[AbsoluteVacuum]

In mumax-view (https://mumax.ugent.be/mumax-view) both scroll up and scroll down zoom out, which makes it impossible to zoom in.

[JonathanMaes]

It seems that the library used for the 3D visualisation has at some point made scrolling more uniform across platforms.

In index.html there are some Module._setScrollSensitivity calls, whose appropriate values have since changed. For example, for Firefox on Windows nowadays a value of -0.003 works well to avoid the aforementioned issue, while currently the value for that browser set in index.html is -0.1.