Scale down endgames with pawns on one or two adjacent files

src/pawns.h

@@ -45,6 +45,10 @@ struct Entry {
     return semiopenFiles[c] & (leftSide ? (1 << f) - 1 : ~((1 << (f + 1)) - 1));
   }
 
+  int pawn_span(Color c) const {
+    return pawnSpan[c];
+  }
+
   int pawns_on_same_color_squares(Color c, Square s) const {
     return pawnsOnSquares[c][!!(DarkSquares & s)];
   }
@@ -71,6 +75,7 @@ struct Entry {
   int minKPdistance[COLOR_NB];
   int castlingRights[COLOR_NB];
   int semiopenFiles[COLOR_NB];
+  int pawnSpan[COLOR_NB];
   int pawnsOnSquares[COLOR_NB][COLOR_NB]; // [color][light/dark squares]
 };