Revisit the Python templates in Qt Creator

Qt Creator offers only a minimal set of templates for the Python developers:

• Empty application: empty Qt application with PySide imports
• Empty window: Simple widget based application with imports
• Window UI: project based on a .ui file
• Qt Quick Application - Empty: empty qml load from Python

There is still some missing use-cases that might be very beneficial for people that's using PySide in Qt Creator:

• Qt Quick Application - initial properties: to set some initial data from Python
• Qt Quick Application - Python QML element: to declare a Python class as QML element so it's used from QML.
• Qt Quick Application - Python model: expose to QML an implementation of a Q*Model via qmlRgisterSingletonType.

other ideas are:

• Qt Quick Application - Extend QML object with python slots
• Qt Quick Application - Custom Property