Fix #889 (wrong color to play)

[kaorahi]

(Caution: You also need to apply #766 to handle initial stones correctly in Lizzie 0.7.4.)

This patch fixes both #889 and another issue (handicap stones are not cleared for background engines) in Lizzie 0.7.3:

1. Start Lizzie.
2. Paste (;AB[dd]).
3. Switch the engine to Engine1.
4. Click "ClearBoard" button in the toolbar.
5. Switch the engine to Engine0 again.
6. Click "Analyze > Clear analysis" in the menu.

The board is empty at 6, but no candidate appears around the top left corner.

Notes

This patch is just a workaround. It will be better to specify player explicitly in lz-analyze like lz-analyze b 10 instead of lz-analyze 10. I did not do it this time because I am not sure whether Lizzie.board.getData().blackToPlay (or Lizzie.board.getHistory().isBlacksTurn()) is always updated correctly before pondering.

[kaorahi]

Ideally, we should support PL property in SGF to specify who to play if there are both black and white stones in the initial setup. See also Katrain's smarter way. sanderland/katrain#293