Prevent zoom when a modal is open

It was bugging me that the zoom is working when a modal is open (annoying when you're browsing the made critters for example). So this quick fix prevents this behavior.

Like for the other PR the diff is [huge because of whitespaces](https://github.com/romainberger/voxel-painter/commit/ba5b29bcd776b7869777657bbf43a15bd01b9614?w=1).