The current code ignores magnitude differences in deltaY, resulting in an experience that is either too fast on trackpad or too slow with a mousewheel.

This change allows those to differ within a clamped range, so that one zoomSpeed value works well for both input devices.

Fixes visjs#1882

Otherwise, right-to-left horizontal edges with middle-aligned labels would have their labels rendered at the origin.

This makes the actual problems in the code easier to find