Use hardware layers in more situations

* Turn on while dragging
* Fix bug: don't disable when swiping pages during drag
* Fix bug: disable hardware layers on startup
* Removing old state code in Workspace

Change-Id: I5633dc98f2679784aea5551564dfa19504a074a6

src/com/android/launcher2/PagedView.java

@@ -301,13 +301,17 @@ public abstract class PagedView extends ViewGroup {
     }
 
     protected void pageBeginMoving() {
-        mIsPageMoving = true;
-        onPageBeginMoving();
+        if (!mIsPageMoving) {
+            mIsPageMoving = true;
+            onPageBeginMoving();
+        }
     }
 
     protected void pageEndMoving() {
-        onPageEndMoving();
-        mIsPageMoving = false;
+        if (mIsPageMoving) {
+            mIsPageMoving = false;
+            onPageEndMoving();
+        }
     }
 
     protected boolean isPageMoving() {