Update ImpedanceModel.load and save

mbtrack2/impedance/impedance_model.py

@@ -507,7 +507,8 @@ class ImpedanceModel():
 
         """
         to_save = {"wakefields":self.wakefields,
-                   "positions":self.positions}
+                   "positions":self.positions,
+                   "names":self.names}
         with open(file,"wb") as f:
             pickle.dump(to_save, f)
     
@@ -533,6 +534,6 @@ class ImpedanceModel():
             to_load = pickle.load(f)
             
         self.wakefields = to_load["wakefields"]
-        self.positions = to_load["positions"]  
-        self.sum_elements()
-        self.sum_by_name_all()
+        self.positions = to_load["positions"]
+        self.names = to_load["names"]
+        self.compute_sum()