Revert evaluation cache

And return on using TT as backing store for position
evaluations.

Tests (even on single thread) show eval cache was a regression.
In multi thread result should be even worst because eval cache
is a per-thread struct, while TT is shared.

After 4957 games at 15"+0.05 (single thread)
eval cache vs master 969 - 1093 - 2895  -9 ELO

So previous reported result of +18 ELO was probably due to an
issue in the testing framework (a bug in cutechess-cli) that
has been fixed in the meanwhile.

bench: 5386711

src/evaluate.h

@@ -20,7 +20,6 @@
 #if !defined(EVALUATE_H_INCLUDED)
 #define EVALUATE_H_INCLUDED
 
-#include "misc.h"
 #include "types.h"
 
 class Position;
@@ -31,16 +30,6 @@ extern void init();
 extern Value evaluate(const Position& pos, Value& margin);
 extern std::string trace(const Position& pos);
 
-const int TableSize = 262144;
-
-struct Entry {
-  Key key;
-  Value value;
-  int16_t margins[2];
-};
-
-struct Table : HashTable<Entry, TableSize> {};
-
 }
 
 #endif // !defined(EVALUATE_H_INCLUDED)