Change move_is_ok() and square_is_ok() in something useful

As is defined now is always true, tested with:

  for (long i=-1000000; i < 1000000; i++)
      if (!move_is_ok(Move(i)))
          exit(0);

Reason is that move_from() and move_to() already truncate the
input value to something in the range [0, 63] that is always
a possible square.

So change definition to something useful.

The same applies also to square_is_ok()

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/move.cpp

@@ -135,7 +135,7 @@ const std::string move_to_uci(Move move, bool chess960) {
 }
 
 
-/// Overload the << operator, to make it easier to print moves.
+/// Overload the << operator, to make it easier to print moves
 
 std::ostream& operator << (std::ostream& os, Move m) {
 
@@ -144,9 +144,9 @@ std::ostream& operator << (std::ostream& os, Move m) {
 }
 
 
-/// move_is_ok(), for debugging.
+/// move_is_ok(), for debugging
 
 bool move_is_ok(Move m) {
 
-  return square_is_ok(move_from(m)) && square_is_ok(move_to(m));
+  return move_from(m) != move_to(m); // Catches also MOVE_NONE
 }