Create a UCI Training option

Creates a UCI Training option and uses it to disable LMP on PV nodes.

src/ucioption.cpp

@@ -69,6 +69,7 @@ void init(OptionsMap& o) {
   o["Move Overhead"]         << Option(10, 0, 5000);
   o["Slow Mover"]            << Option(100, 10, 1000);
   o["nodestime"]             << Option(0, 0, 10000);
+  o["Training"]              << Option(false);
   o["UCI_Chess960"]          << Option(false);
   o["UCI_AnalyseMode"]       << Option(false);
   o["UCI_LimitStrength"]     << Option(false);