Stop using non-standard, deprecated wheel events

Replaces:
https://developer.mozilla.org/en-US/docs/Web/API/MouseWheelEvent
https://developer.mozilla.org/en-US/docs/Web/API/Element/DOMMouseScroll_event

With:
https://developer.mozilla.org/en-US/docs/Web/API/WheelEvent

Author: Joncom

lib/impact/input.js

@@ -116,9 +116,7 @@ ig.Input = ig.Class.extend({
 	initMouse: function() {
 		if( this.isUsingMouse ) { return; }
 		this.isUsingMouse = true;
-		var mouseWheelBound = this.mousewheel.bind(this);
-		ig.system.canvas.addEventListener('mousewheel', mouseWheelBound, false );
-		ig.system.canvas.addEventListener('DOMMouseScroll', mouseWheelBound, false );
+		ig.system.canvas.addEventListener('wheel', this.mousewheel.bind(this), false );
 
 		ig.system.canvas.addEventListener('contextmenu', this.contextmenu.bind(this), false );
 		ig.system.canvas.addEventListener('mousedown', this.keydown.bind(this), false );
@@ -157,8 +155,7 @@ ig.Input = ig.Class.extend({
 
 
 	mousewheel: function( event ) {
-		var delta = event.wheelDelta ? event.wheelDelta : (event.detail * -1);
-		var code = delta > 0 ? ig.KEY.MWHEEL_UP : ig.KEY.MWHEEL_DOWN;
+		var code = event.deltaY < 0 ? ig.KEY.MWHEEL_UP : ig.KEY.MWHEEL_DOWN;
 		var action = this.bindings[code];
 		if( action ) {
 			this.actions[action] = true;
@@ -319,4 +316,4 @@ ig.Input = ig.Class.extend({
 	}
 });
 
-});
+});