Fix drag coordinates with camera zoom (issue 4755)

The dragX and dragY passed to 'dragStart' and 'drag' events are supported to be in world coordinates (as specified by the docs) but the coordinates used (pointer.x and pointer.y) were not transformed by the camera into world space. The drags now use pointer.worldX and pointer.worldY which are the post-transform coordinates.

Author: hh-jay

src/input/InputPlugin.js

@@ -1126,8 +1126,8 @@ var InputPlugin = new Class({
             input.dragStartX = gameObject.x;
             input.dragStartY = gameObject.y;
 
-            input.dragStartXGlobal = pointer.x;
-            input.dragStartYGlobal = pointer.y;
+            input.dragStartXGlobal = pointer.worldX;
+            input.dragStartYGlobal = pointer.worldY;
 
             input.dragX = input.dragStartXGlobal - input.dragStartX;
             input.dragY = input.dragStartYGlobal - input.dragStartY;
@@ -1330,13 +1330,13 @@ var InputPlugin = new Class({
 
             if (!gameObject.parentContainer)
             {
-                dragX = pointer.x - input.dragX;
-                dragY = pointer.y - input.dragY;
+                dragX = pointer.worldX - input.dragX;
+                dragY = pointer.worldY - input.dragY;
             }
             else
             {
-                var dx = pointer.x - input.dragStartXGlobal;
-                var dy = pointer.y - input.dragStartYGlobal;
+                var dx = pointer.worldX - input.dragStartXGlobal;
+                var dy = pointer.worldY - input.dragStartYGlobal;
 
                 var rotation = gameObject.getParentRotation();