Fix shift-scrolling on Macs

This turns into horizontal scroll input, so we just
use deltaX when shift is held.

macrovision.js

@@ -4192,10 +4192,19 @@ document.addEventListener("DOMContentLoaded", () => {
         }
     }
     document.querySelector("#world").addEventListener("wheel", e => {
-        const magnitude = Math.abs(e.deltaY / 100);
+        let magnitude = Math.abs(e.deltaY / 100);
+
         if (shiftHeld) {
+            // macs do horizontal scrolling with shift held
+            
+            let delta = e.deltaY
+
+            if (e.deltaY == 0) {
+                magnitude = Math.abs(e.deltaX / 100)
+                delta = e.deltaX
+            }
             if (selected) {
-                let dir = e.deltaY > 0 ? 10 / 11 : 11 / 10;
+                let dir = delta > 0 ? 10 / 11 : 11 / 10;
                 dir -= 1;
                 dir *= magnitude;
                 dir += 1;