-Systematically show init+dest squares in PGN, maybe after short notation
-(2 moves list, second for de-ambiguification)
-Button to show all pieces that can move (next to expert mode; change icons)
-
-Bugs, limitations:
- - switching chess when castling: show 2 promotion kings (??)
- - Crazyhouse: TODO = keep track of promoted pawns.
- - Checkered: implement stage 2 ?!