Leave parent default QAbstractItemModel

The parent in the createIndex function from QAbstractItemModel refers to a
datamodel, not a GUI component. Setting it incorrectly results in ASSERT
failure in the QAbstractItemView::setModel.

Fixed a minor bug with defaults for iteration number as well

ert_gui/ertwidgets/models/all_cases_model.py

@@ -15,7 +15,7 @@ def __init__(self):
         self.__data = []
 
     def index(self, row, column, parent=None, *args, **kwargs):
-        return self.createIndex(row, column, parent)
+        return self.createIndex(row, column)
 
     def parent(self, index=None):
         return QModelIndex()

ert_gui/tools/load_results/load_results_model.py

@@ -67,7 +67,7 @@ def getIterationCount():
         iteration = 0
         valid_directory = True
         while valid_directory:
-            formatted = run_path % (0, iteration)
+            formatted = run_path % (0, iteration + 1)
             valid_directory = os.path.exists(formatted)
             if valid_directory:
                 iteration += 1

ert_gui/tools/plot/data_type_keys_list_model.py

@@ -27,7 +27,7 @@ def keyManager(self):
         return self.__ert.getKeyManager()
 
     def index(self, row, column, parent=None, *args, **kwargs):
-        return self.createIndex(row, column, parent)
+        return self.createIndex(row, column)
 
     def parent(self, index=None):
         return QModelIndex()