merge "Provide WDL statistics"

110068808b
https://github.com/official-stockfish/Stockfish/pull/2778
https://github.com/official-stockfish/Stockfish/pull/2788

src/ucioption.cpp

@@ -75,6 +75,7 @@ void init(OptionsMap& o) {
   o["UCI_AnalyseMode"]       << Option(false);
   o["UCI_LimitStrength"]     << Option(false);
   o["UCI_Elo"]               << Option(1350, 1350, 2850);
+  o["UCI_ShowWDL"]           << Option(false);
   o["SyzygyPath"]            << Option("<empty>", on_tb_path);
   o["SyzygyProbeDepth"]      << Option(1, 1, 100);
   o["Syzygy50MoveRule"]      << Option(true);