Editing the turn/position in the study chapter edit form

[johndoknjas]

• Enhancement: adding an option to change whose turn it is and/or edit the board. Maybe this option is only available if no moves/annotations have been made in the chapter yet. For myself I find that sometimes I set up a position/puzzle slightly wrong, and then correcting it requires making a new chapter and deleting the old one.

[SergioGlorias]

It would be good to separate the 2 topics and do everything together.
will help devs focus on each topic