GitLab

  (solitaire-mode): Define with `define-derived-mode'.
  (solitaire-insert-board, solitaire-right, solitaire-left, solitaire-up)
  (solitaire-down): Use "?\s" instead of "?\ "; use `when'.
  (solitaire-undo, solitaire-check): Use `when'.
  (solitaire-solve): Err out if the solitaire is already in progress.
  Use `when'.