Undo doesn't return the turn to the previous player

[melvic-ybanez]

To replicate:

1. Move a white piece.
2. Click on a black piece
3. Undo
4. Try clicking the white piece again.

Expected behavior: White piece should be clickable again
Actual behavior: White piece can't be clicked.

In some cases the it can even cause weird behaviors. For instance, if the black piece you clicked is a pawn, and the white piece happens to be at the end row. If you clicked the white piece again the system will think you are moving the black pawn to the last destination, causing the promotion dialog to appear.