search: Adjust TranspositionTable::save params

like morris 0.2, but not same.

Use:
TranspositionTable::boundType(bestValue, alpha, beta),
Not use oldAlpha

self play change last few moves, white win more quickly.

From:
(3,5)->(2,5)
(1,5)->(1,4)
(2,5)->(1,5)
(1,6)->(1,7)
(1,5)->(1,6)
(1,7)->(2,7)
-(2,4)
(1,6)->(1,5)
(2,7)->(1,7)
(1,5)->(1,6)
(1,7)->(2,7)
-(1,2)
Player2 win!

To:
(3,5)->(2,5)
(1,6)->(1,7)
(2,5)->(3,5)
(1,7)->(2,7)
-(2,4)
(3,5)->(2,5)
(1,5)->(1,6)
-(1,2)
Player2 win!

src/search.cpp

@@ -473,8 +473,7 @@ Value search(Position *pos, Sanmill::Stack<Position> &ss, Depth depth, Depth ori
 #ifdef TRANSPOSITION_TABLE_ENABLE
     TranspositionTable::save(bestValue,
                              depth,
-                             bestValue >= beta ? BOUND_LOWER :
-                             BOUND_UPPER,
+                             TranspositionTable::boundType(bestValue, alpha, beta),
                              posKey
 #ifdef TT_MOVE_ENABLE
                              , bestMove