Fix compile on icc

Error is:

  a value of type "int" cannot be assigned to an entity of type "Value"

Also retire the now unused squares_of_color() function.

No functional change.

src/evaluate.cpp

@@ -124,7 +124,8 @@ namespace {
       S( 94, 99), S( 96,100), S(99,111), S(99,112) }
   };
 
-  // Outpost[knight/bishop][supported by pawn]
+  // Outpost[knight/bishop][supported by pawn] contains bonuses for knights and bishops
+  // outposts, bigger if outpost piece is supported by a pawn.
   const Score Outpost[][2] = {
     { S(28, 7), S(42,11) }, // Knights
     { S(12, 3), S(18, 5) }  // Bishops