Manually Sort Finished

Recently, I have been working on manually sort in digikam. User can sort images manually in digikam icon view.
We have an album like below:

User drag picture 0 and drop it on picture 3. There will be a menu which has a "Put back" action.

After click "Put back", picture 0 will be behind picture 3. The order of all the pictures will be recorded in database.

I added an action in View-Sort Items, which is called "By Manual". User can restore the manually sort result by click on "By Manual".

The code can be found here.