Tweak history updates

In general the history update bonus is slightly decreased by 11% which gives a slower saturation speed.
In addition only for main history the divisor is halfed (used history values are doubled to maintain same maximum)
which have an effect in the opposite direction on saturation speed.

STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 157088 W: 42673 L: 42168 D: 72247
Ptnml(0-2): 857, 17346, 41642, 17833, 866
https://tests.stockfishchess.org/tests/view/62e5517ab383a712b13867c5

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 325592 W: 88705 L: 87753 D: 149134
Ptnml(0-2): 594, 32288, 96076, 33248, 590
https://tests.stockfishchess.org/tests/view/62e5e4f4b383a712b1387d53

closes https://github.com/official-stockfish/Stockfish/pull/4119

Bench: 5518728

src/movepick.cpp

@@ -137,7 +137,7 @@ void MovePicker::score() {
                    +     (*captureHistory)[pos.moved_piece(m)][to_sq(m)][type_of(pos.piece_on(to_sq(m)))];
 
       else if constexpr (Type == QUIETS)
-          m.value =      (*mainHistory)[pos.side_to_move()][from_to(m)]
+          m.value =  2 * (*mainHistory)[pos.side_to_move()][from_to(m)]
                    + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
                    +     (*continuationHistory[1])[pos.moved_piece(m)][to_sq(m)]
                    +     (*continuationHistory[3])[pos.moved_piece(m)][to_sq(m)]
@@ -155,7 +155,7 @@ void MovePicker::score() {
               m.value =  PieceValue[MG][pos.piece_on(to_sq(m))]
                        - Value(type_of(pos.moved_piece(m)));
           else
-              m.value =      (*mainHistory)[pos.side_to_move()][from_to(m)]
+              m.value =  2 * (*mainHistory)[pos.side_to_move()][from_to(m)]
                        + 2 * (*continuationHistory[0])[pos.moved_piece(m)][to_sq(m)]
                        - (1 << 28);
       }

src/movepick.h

@@ -87,7 +87,7 @@ enum StatsType { NoCaptures, Captures };
 /// ordering decisions. It uses 2 tables (one for each color) indexed by
 /// the move's from and to squares, see www.chessprogramming.org/Butterfly_Boards
 /// (~11 elo)
-typedef Stats<int16_t, 14365, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
+typedef Stats<int16_t, 7183, COLOR_NB, int(SQUARE_NB) * int(SQUARE_NB)> ButterflyHistory;
 
 /// CounterMoveHistory stores counter moves indexed by [piece][to] of the previous
 /// move, see www.chessprogramming.org/Countermove_Heuristic

src/search.cpp

@@ -81,7 +81,7 @@ namespace {
 
   // History and stats update bonus, based on depth
   int stat_bonus(Depth d) {
-    return std::min((9 * d + 270) * d - 311 , 2145);
+    return std::min((8 * d + 240) * d - 276 , 1907);
   }
 
   // Add a small random component to draw evaluations to avoid 3-fold blindness
@@ -1033,7 +1033,7 @@ moves_loop: // When in check, search starts here
                   && history < -3875 * (depth - 1))
                   continue;
 
-              history += thisThread->mainHistory[us][from_to(move)];
+              history += 2 * thisThread->mainHistory[us][from_to(move)];
 
               // Futility pruning: parent node (~9 Elo)
               if (   !ss->inCheck
@@ -1171,7 +1171,7 @@ moves_loop: // When in check, search starts here
           if ((ss+1)->cutoffCnt > 3 && !PvNode)
               r++;
 
-          ss->statScore =  thisThread->mainHistory[us][from_to(move)]
+          ss->statScore =  2 * thisThread->mainHistory[us][from_to(move)]
                          + (*contHist[0])[movedPiece][to_sq(move)]
                          + (*contHist[1])[movedPiece][to_sq(move)]
                          + (*contHist[3])[movedPiece][to_sq(move)]