🐛 Propagate _isIncrementalEval value in Position 'clone' constructor

[eduherminio]

Test  | bugfix/propagate-isIncremental-eval-clone-constructor
Elo   | -4.75 +- 4.15 (95%)
SPRT  | 6.0+0.06s Threads=1 Hash=32MB
LLR   | -2.29 (-2.25, 2.89) [-5.00, 0.00]
Games | 11846: +3306 -3468 =5072
Penta | [322, 1420, 2577, 1306, 298]
https://openbench.lynx-chess.com/test/1238/

Test  | bugfix/propagate-isIncremental-eval-clone-constructor
Elo   | 1.49 +- 3.68 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=32MB
LLR   | 2.91 (-2.25, 2.89) [-5.00, 0.00]
Games | 14730: +4133 -4070 =6527
Penta | [325, 1767, 3186, 1694, 393]
https://openbench.lynx-chess.com/test/1240/