basic object oriented programming concepts.
Lab: Graphical User Interfaces
Use object oriented design to make a graphical user interface in Qt.
Add a few extra explanations about Qt.

Remove tabs in web navigator project.
Make lab classify consistently with other Python labs.
Lab: Object Oriented Programming
Lab: Graphical User Interfaces
added a section on paradigms

Also included a problem that assigns reading for class magic methods.
Merge pull request #195 from ayr0/paradigms

Object oriented programming