Trying to track down corrupt database / items disappearing

-> Adding logs for all database transactions
-> Adding sanity checks for items in folders, throwing exceptions
   if they are violated
-> Reducing database upates when re-arranging items, only
   update if values have changed
-> Removed some dead code from ItemInfo (isGesture?)

Change-Id: Ia5cd57d92082f633dbf4aa5d64612cbae2d82bb4

src/com/android/launcher2/Workspace.java

@@ -3383,7 +3383,8 @@ public class Workspace extends SmoothPagedView
             View v = cl.getShortcutsAndWidgets().getChildAt(i);
             ItemInfo info = (ItemInfo) v.getTag();
             // Null check required as the AllApps button doesn't have an item info
-            if (info != null) {
+            if (info != null && info.requiresDbUpdate) {
+                info.requiresDbUpdate = false;
                 LauncherModel.modifyItemInDatabase(mLauncher, info, container, screen, info.cellX,
                         info.cellY, info.spanX, info.spanY);
             }