Save and restore last selected cell

[timo-a]

If the orientation changes

1. the position of the currently selected cell is saved.
2. the activity is restarted
3. the cell of the stored position is then automatically selected as "enter solution" (-> red)

What should be done:

1. if the current cell is marked for note input (yellow), then it should also be restored as note input and not (as it currently is) as solution input

2. if the game is interrupted the last selected position is not persisted but only the last action is restored from the action tree -> persist last selection and selection mode.