refactor(GalaxyMapCluster): add DefaultStroke property for stroke color logic

  Class GalaxyMapCluster: +added DefaultStroke property (determines stroke color based on cluster state)

refactor(GalaxyMapViewer): reset cluster reference on sector removal

  Class GalaxyMapViewer: +set cluster.Cluster to null when removing a sector; +set Sector to null when removing a cluster

Author: chemodun

src/X4Map/GalaxyMapCluster.cs

@@ -116,6 +116,18 @@ protected double Height
       (HexagonCorner.LeftBottom, HexagonCorner.RightBottom),
     ];
 
+    protected Brush DefaultStroke
+    {
+      get
+      {
+        if (Cluster == null)
+        {
+          return Brushes.DarkGray;
+        }
+        return Cluster.Source == "New" ? Brushes.DarkGreen : Brushes.Black;
+      }
+    }
+
     public virtual double Create(GalaxyMapViewer map)
     {
       double maxInternalSizeKm = 0;

src/X4Map/GalaxyMapViewer.cs

@@ -576,6 +576,7 @@ public void RemoveCluster(GalaxyMapCluster cluster)
         _sectors.Remove(sector);
       }
       cluster.Sectors.Clear();
+      cluster.Cluster = null;
     }
 
     public void RemoveSector(GalaxyMapSector sector)
@@ -595,6 +596,7 @@ public void RemoveSector(GalaxyMapSector sector)
           RemoveCluster(ownerCluster);
         }
       }
+      Sector = null;
     }
 
     protected void RefreshConnectionsForCluster(GalaxyMapCluster updatedCluster)