New way to swap/move item fromIndex toIndex

#1

in BNRItemStore.m

- (void)moveItemAtIndex:(NSUInteger)fromIndex
                     to:(NSUInteger)toIndex{
    if(fromIndex == toIndex){
        return;
    }
    
    /* What's suggested in the book to swap "from" with "to"
    BNRItem *item = self.privateItems[fromIndex];
    [self.privateItems removeObjectAtIndex:fromIndex];
    [self.privateItems insertObject:item atIndex:toIndex];
     */

    //New way to swap "from" with "to", which is a little bit efficient as you don't have to remove/insert item
    BNRItem *temp = self.privateItems[toIndex];
    self.privateItems[toIndex] = self.privateItems[fromIndex];
    self.privateItems[fromIndex] = temp;
}