supporting swipable home screens on xlarge devices

- icons and widgets on home screens can be "dimmed"
- celllayout no longer renders a dimmed version of itself, but instead its children make dimmed versions of themselves
- celllayout no longer always takes up full size of workspace, in landscape mode 
neighboring screens (celllayouts) are visible
- on xlarge devices, in landscape mode side screens are "dimmed"
- moved holographic outline helper to its own file
- fixed bug where mini-screens were still able to scroll left/right

Change-Id: I9e85ab4147edfae1e7525c3d11d42be3fabf4f6d

src/com/android/launcher2/SmoothPagedView.java

@@ -110,7 +110,7 @@ public abstract class SmoothPagedView extends PagedView {
         whichPage = Math.max(0, Math.min(whichPage, getChildCount() - 1));
 
         final int screenDelta = Math.max(1, Math.abs(whichPage - mCurrentPage));
-        final int newX = whichPage * getWidth();
+        final int newX = getChildOffset(whichPage) - getRelativeChildOffset(whichPage);
         final int delta = newX - mScrollX;
         int duration = (screenDelta + 1) * 100;