Add linear tiled window animations

src/compositor.rs

@@ -360,6 +360,10 @@ fn start_compositor2(
         cpu_worker,
         ui_drag_enabled: Cell::new(true),
         ui_drag_threshold_squared: Cell::new(10),
+        animations: Default::default(),
+        layout_animations_requested: Default::default(),
+        layout_animations_active: Default::default(),
+        suppress_animations_for_next_layout: Default::default(),
         toplevels: Default::default(),
         const_40hz_latch: Default::default(),
         tray_item_ids: Default::default(),