added support for dragging widgets and app icons to mini screens

- gave mini screens a rounded rect background
- mini screens change color when dragged over
- added a way to specify the active region of dragged items, to allow for clipping of whitespace at borders
- fixed: feedback while dragging was often one cell off
- fixed: bug when adding to almost-full screen
- removed unused classes

Change-Id: I2fbd2aaaee6831b288cca8dec75e7b446068e8d1

src/com/android/launcher2/AllAppsPagedView.java

@@ -181,7 +181,6 @@ public class AllAppsPagedView extends PagedView
         app = new ApplicationInfo(app);
 
         mDragController.startDrag(v, this, app, DragController.DRAG_ACTION_COPY);
-        mLauncher.closeAllApps(true);
         return true;
     }