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/CellLayout.java

@@ -2148,6 +2148,10 @@ public class CellLayout extends ViewGroup {
             // We do a null check here because the item info can be null in the case of the
             // AllApps button in the hotseat.
             if (info != null) {
+                if (info.cellX != lp.tmpCellX || info.cellY != lp.tmpCellY ||
+                        info.spanX != lp.cellHSpan || info.spanY != lp.cellVSpan) {
+                    info.requiresDbUpdate = true;
+                }
                 info.cellX = lp.cellX = lp.tmpCellX;
                 info.cellY = lp.cellY = lp.tmpCellY;
                 info.spanX = lp.cellHSpan;