Retire neighboring_files_bb() overload

Rarely used and we prefer to not hide the complexity.

No functional change.

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

src/main.cpp

@@ -35,7 +35,7 @@ extern void kpk_bitbase_init();
 
 int main(int argc, char* argv[]) {
 
-  init_bitboards();
+  bitboards_init();
   Position::init();
   kpk_bitbase_init();
   Search::init();