-Added 3D effect to home screen scrolling

-Added background outline fade in / out
-Modified the feel of scrolling: now using quintic
 interpolator and modified the influence of
 scroll velocity

Change-Id: Ifddcab5223ac20be7d9f800ccf09442d9b4db781

src/com/android/launcher2/Dimmable.java

@@ -0,0 +1,6 @@
+package com.android.launcher2;
+
+public interface Dimmable {
+    public void setDimmableProgress(float progress);
+    public float getDimmableProgress();
+}