Expose caravan meeting spot and auto select supplies status (#389)

As the `meetingSpot` field needs to be re-assigned outside of constructor (passed by ref), it no longer can be readonly.

Co-authored-by: Sokyran <toCy&#$VIH$1cSOu8s&Fv@UVN%L3snN*H09$1^Xghq*hKo9Itnmq#bNf8Ld67#T$#a&cEaY1>

Source/Client/Persistent/CaravanFormingSession.cs

@@ -20,7 +20,7 @@ public class CaravanFormingSession : IExposable, ISessionWithTransferables, IPau
         public int destinationTile = -1;
         public List<TransferableOneWay> transferables;
         public bool autoSelectTravelSupplies;
-        public readonly IntVec3? meetingSpot;
+        public IntVec3? meetingSpot;
 
         public bool uiDirty;
 
@@ -162,6 +162,8 @@ public void ExposeData()
             Scribe_Values.Look(ref mapAboutToBeRemoved, "mapAboutToBeRemoved");
             Scribe_Values.Look(ref startingTile, "startingTile");
             Scribe_Values.Look(ref destinationTile, "destinationTile");
+            Scribe_Values.Look(ref autoSelectTravelSupplies, "autoSelectTravelSupplies");
+            Scribe_Values.Look(ref meetingSpot, "meetingSpot");
 
             Scribe_Collections.Look(ref transferables, "transferables", LookMode.Deep);
         }