Merge branch 'eval_cache'

Use an eval cache instead of TT to store node
position evaluations.

It is already an improvment and, because it frees
two TT entry slots, paves the way to extend TT to
store both upper and lower bounds.

After 4855 games, single thread, 15"+0.05
Mod vs Orig 1165 -920 - 2770 ELO +18

bench: 5149248

src/thread.h

@@ -22,6 +22,7 @@
 
 #include <vector>
 
+#include "evaluate.h"
 #include "material.h"
 #include "movepick.h"
 #include "pawns.h"
@@ -108,6 +109,7 @@ public:
   void wait_for_stop_or_ponderhit();
 
   SplitPoint splitPoints[MAX_SPLITPOINTS_PER_THREAD];
+  Eval::Table evalTable;
   MaterialTable materialTable;
   PawnTable pawnTable;
   size_t idx;