[Fix] Remove parameters MetaModel, Model, ExpDesign from PostProcessing

PostProcessing uses engine.* instead of self.* for MetaModel, Model and ExpDesign.
In addition it calls the engine properties instead of Model properties where possible

src/bayesvalidrox/post_processing/post_processing.py

@@ -69,7 +69,6 @@ class PostProcessing:
 
         bar_plot = True if plot_type == 'bar' else False
         meta_model_type = self.engine.MetaModel.meta_model_type
-        meta_model_type = self.engine.MetaModel.meta_model_type
 
         # Read Monte-Carlo reference
         self.mc_reference = self.engine.Model.read_observation('mc_ref')
@@ -765,7 +764,6 @@ class PostProcessing:
                 total_sobol_all[k][i] = v
 
         self.total_sobol = {}
-        for output in self.engine.out_names:
         for output in self.engine.out_names:
             self.total_sobol[output] = np.mean(total_sobol_all[output], axis=0)
 
@@ -775,7 +773,6 @@ class PostProcessing:
 
         fig = plt.figure()
 
-        for outIdx, output in enumerate(self.engine.out_names):
         for outIdx, output in enumerate(self.engine.out_names):
 
             # Extract total Sobol indices