ENH: Remove unneeded instance variable related to Endoscopy model export

Following cc0ee37 (ENH: Update Endoscopy removing obsolete "model"
cursor type), there is no need to keep track of the model instance. User
may retrieve the model node by its name set as "Path-{curveName}".

Modules/Scripted/Endoscopy/Endoscopy.py

@@ -73,7 +73,6 @@ def __init__(self, parent=None):
 
         self.transform = None
         self.cursor = None
-        self.model = None
         self.skip = 0
         self.logic = None
         self.timer = qt.QTimer()
@@ -394,7 +393,7 @@ def onCreatePathButtonClicked(self):
         # Hide the cursor, model and inputCurve from the main 3D view
         EndoscopyWidget._hideOnlyInView(
             EndoscopyWidget._viewNodeIDFromCameraNode(self.cameraNode),
-            [self.cursor, self.model, self.inputCurve],
+            [self.cursor, inputCurve],
         )
 
         # Update flythrough variables
@@ -491,12 +490,10 @@ def onSaveExportModelButtonClicked(self):
         if self.transform:
             model.model.SetNodeReferenceID("CameraTransform", self.transform.GetID())
 
-        self.model = model.model
-
         # Hide the model from the main 3D view
         EndoscopyWidget._hideOnlyInView(
             EndoscopyWidget._viewNodeIDFromCameraNode(self.cameraNode),
-            [self.model],
+            [model.model],
         )
         logging.debug("-> Model created")