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/DropTarget.java

@@ -120,7 +120,7 @@ public interface DropTarget {
 
     // These methods are implemented in Views
     void getHitRect(Rect outRect);
-    void getLocationOnScreen(int[] loc);
+    void getLocationInDragLayer(int[] loc);
     int getLeft();
     int getTop();
 }