feat: add excludeStandaloneWagons to optimize performance (TeamOpenIndustry#1576)

Author: Goldenfield192

src/main/java/cam72cam/immersiverailroading/Config.java

@@ -257,6 +257,9 @@ public static class ConfigDebug {
 		@Comment("Keep rolling stock loaded even when it is not moving")
 		public static boolean keepStockLoaded = true;
 
+		@Comment("Exclude unattached wagons from chunk loading when keepStockLoaded is true")
+		public static boolean excludeStandaloneWagons = false;
+
 		@Comment( "Print extra chunk loading info" )
 		public static boolean debugLog = false;
 

src/main/java/cam72cam/immersiverailroading/entity/EntityCoupleableRollingStock.java

@@ -100,6 +100,7 @@ public String toString() {
 	@TagSync
 	@TagField("hasElectricalPower")
 	private boolean hasElectricalPower;
+	private boolean linkedToLocomotive;
 	private boolean hadElectricalPower = false;
 	private int gotElectricalPowerTick = -1;
 
@@ -186,17 +187,23 @@ public void onTick() {
 
 		if (this.getTickCount() % 5 == 0) {
 			hasElectricalPower = false;
-			this.mapTrain(this, false, stock ->
-					hasElectricalPower = hasElectricalPower ||
-							stock instanceof Locomotive && ((Locomotive) stock).providesElectricalPower()
+			linkedToLocomotive = false;
+			this.mapTrain(this, false, stock -> {
+							  hasElectricalPower = hasElectricalPower ||
+									  stock instanceof Locomotive && ((Locomotive) stock).providesElectricalPower();
+							  linkedToLocomotive = linkedToLocomotive || stock instanceof Locomotive;
+						  }
 			);
 		}
 
 		hadElectricalPower = hasElectricalPower();
 
 		if (this.getCurrentState() != null && !this.getCurrentState().atRest || ConfigDebug.keepStockLoaded) {
-			keepLoaded();
-		}
+			//Then exclude stocks not linked to any locomotive
+            if (!ConfigDebug.excludeStandaloneWagons || this.linkedToLocomotive) {
+                keepLoaded();
+            }
+        }
 
 		slackFrontPercent = 0;
 		slackRearPercent = 0;