Use webbrowser instead of get_available_screencast_viewer (#745)

* improve opening tutorial

* improve show_tutorial_dialog

* improve show_tutorial_dialog

* remove not implemented

* remove unncessary package QtWebEngineWidgets

* remove commented import of QtWebEngineWidgets

libs/stringBundle.py

@@ -1,5 +1,10 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
+"""
+if items were added in files in the resources/strings folder,
+then execute "pyrcc5 resources.qrc -o resources.py" in the root directory
+and execute "pyrcc5 ../resources.qrc -o resources.py" in the libs directory
+"""
 import re
 import os
 import sys