Added a method to remove marks

GameMap.py

@@ -28,6 +28,10 @@ class GameMap:
             errorMessage = "The mark" + str((x,y)) + " is beyond preset max values, max_x - " + str(self.max_size_x) + ", max_y - " + str(self.max_size_y)
             raise IndexError(errorMessage)
     
+    
+    def remove_mark(self, x, y):
+        data.pop((x,y))
+        
         
     def clear_map(self):
         self.data = {}