Fix the Python templates

This fixes the templates so that they do not produce any warnings
and also includes QQuickItem in the choice of base classes

Change-Id: I58bbd462052f5d2a64bb8c4bea5bbdcd15e66700
Reviewed-by: Cristian Maureira-Fredes <cristian.maureira-fredes@qt.io>

share/qtcreator/templates/wizards/classes/python/file.py

@@ -21,6 +21,7 @@ from PyQt5 import QtQuick
     @endif
 @endif
 
+
 @if '%{Base}'
 class %{Class}(%{Base}):
 @else
@@ -29,11 +30,9 @@ class %{Class}:
     def __init__(self):
 @if '%{Base}' === 'QWidget'
         QtWidgets.QWidget.__init__(self)
-@endif
-@if '%{Base}' === 'QMainWindow'
+@elif '%{Base}' === 'QMainWindow'
         QtWidgets.QMainWindow.__init__(self)
-@if '%{Base}' === 'QQuickItem'
+@elif '%{Base}' === 'QQuickItem'
         QtQuick.QQuickItem.__init__(self)
 @endif
         pass
-