Use printf() instead of std::cout()

Use printf() instead of std::cout()

Seems sensibly faster: On a

./stockfish bench > /dev/null

We have +2% on mingw and even +5% on MSVC !

Also removed the nice but complex enum set960 machinery,
use directly the underlying move_to_uci() function.

Speed regression reported by Heinz van Saanen.

No functional change.

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