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/LauncherModel.java b/src/com/android/launcher3/LauncherModel.java
index d5dce51..00afd98 100644
--- a/src/com/android/launcher3/LauncherModel.java
+++ b/src/com/android/launcher3/LauncherModel.java
@@ -434,7 +434,7 @@
                 }
             }
         }
-        return CellLayout.findVacantCell(xy, spanX, spanY, xCount, yCount, occupied);
+        return Utilities.findVacantCell(xy, spanX, spanY, xCount, yCount, occupied);
     }
 
     /**