Removing some unused method params from CellLayout

> Replacing various distance calculations with Math.hypot
> Moving findVacantCell to Utilities

Change-Id: I0cb194b603e52b3bb2b29a095bb4da2bb408ab13
diff --git a/src/com/android/launcher3/Folder.java b/src/com/android/launcher3/Folder.java
index dff47c2..1fca7ce 100644
--- a/src/com/android/launcher3/Folder.java
+++ b/src/com/android/launcher3/Folder.java
@@ -459,7 +459,7 @@
 
             int rx = (int) Math.max(Math.max(width - getPivotX(), 0), getPivotX());
             int ry = (int) Math.max(Math.max(height - getPivotY(), 0), getPivotY());
-            float radius = (float) Math.sqrt(rx * rx + ry * ry);
+            float radius = (float) Math.hypot(rx, ry);
             AnimatorSet anim = LauncherAnimUtils.createAnimatorSet();
             Animator reveal = LauncherAnimUtils.createCircularReveal(this, (int) getPivotX(),
                     (int) getPivotY(), 0, radius);