Adapt game specific values to variant duck

This adapts piece and endgame values to variant duck. Attention, use this branch only for variant duck. All other variants are weakened with this game specific values!

src/endgame.cpp

@@ -172,8 +172,8 @@ Value Endgame<KBNK>::operator()(const Position& pos) const {
 template<>
 Value Endgame<KPK>::operator()(const Position& pos) const {
 
-  assert(verify_material(pos, strongSide, VALUE_ZERO, 1));
-  assert(verify_material(pos, weakSide, VALUE_ZERO, 0));
+assert(verify_material(pos, strongSide, VALUE_VIRTUAL_MATE, 1));
+assert(verify_material(pos, weakSide, VALUE_VIRTUAL_LOSS, 0));
 
   // Assume strongSide is white and the pawn is on files A-D
   Square strongKing = normalize(pos, strongSide, pos.square<KING>(strongSide));

src/types.h

@@ -336,6 +336,7 @@ enum Value : int {
   VALUE_MATE      = 32000,
   XBOARD_VALUE_MATE = 200000,
   VALUE_VIRTUAL_MATE = 3000,
+  VALUE_VIRTUAL_LOSS = -3000,
   VALUE_VIRTUAL_MATE_IN_MAX_PLY = VALUE_VIRTUAL_MATE - MAX_PLY,
   VALUE_INFINITE  = 32001,
   VALUE_NONE      = 32002,
@@ -345,11 +346,11 @@ enum Value : int {
   VALUE_MATE_IN_MAX_PLY  =  VALUE_MATE - MAX_PLY,
   VALUE_MATED_IN_MAX_PLY = -VALUE_MATE_IN_MAX_PLY,
 
-  PawnValueMg   = 126,   PawnValueEg   = 208,
-  KnightValueMg = 781,   KnightValueEg = 854,
-  BishopValueMg = 825,   BishopValueEg = 915,
-  RookValueMg   = 1276,  RookValueEg   = 1380,
-  QueenValueMg  = 2538,  QueenValueEg  = 2682,
+  PawnValueMg   = 116,   PawnValueEg   = 186,
+  KnightValueMg = 261,   KnightValueEg = 444,
+  BishopValueMg = 100,   BishopValueEg = 100,
+  RookValueMg   = 204,  RookValueEg   = 244,
+  QueenValueMg  = 427,  QueenValueEg  = 798,
   FersValueMg              = 420,   FersValueEg              = 450,
   AlfilValueMg             = 350,   AlfilValueEg             = 330,
   FersAlfilValueMg         = 700,   FersAlfilValueEg         = 650,