Decouple the usage of PDT evaluator of chart player.

Assets/Cryville/Crtr/RulesetSelectors.cs

@@ -90,10 +90,10 @@ namespace Cryville.Crtr {
 				etor.Optimize(_exp);
 			}
 			public override IEnumerable<ChartEvent> Match(ChartEvent ev) {
-				ChartPlayer.etor.ContextEvent = ev;
-				if (!ChartPlayer.etor.Evaluate(_op, _exp))
+				PdtEvaluator.Instance.ContextEvent = ev;
+				if (!PdtEvaluator.Instance.Evaluate(_op, _exp))
 					throw new EvaluationFailureException();
-				ChartPlayer.etor.ContextEvent = null;
+				PdtEvaluator.Instance.ContextEvent = null;
 				if (_flag) return new ChartEvent[] { ev };
 				else return null;
 			}