Substantially improved performance of dragging and drop animations

-> Took DragView drawing out of the window and put it into the DragLayer
-> Added fade-in/out animations to transition between the final view
   and the DragView, after the view animates
-> Enabled hardware layers on Folder items which improves the
   performance Folder reordering

Change-Id: I4d92ca9fba172d1bab9efc215a99abcaadcdf503

src/com/android/launcher2/ButtonDropTarget.java

@@ -90,4 +90,8 @@ public class ButtonDropTarget extends FrameLayout implements DropTarget, DragCon
     public DropTarget getDropTargetDelegate(DragObject d) {
         return null;
     }
+
+    public void getLocationInDragLayer(int[] loc) {
+        mLauncher.getDragLayer().getLocationInDragLayer(this, loc);
+    }
 }