Refactor Week 4 Notes / exercises

[mmcleod89]

More advanced OOP including

• Inheritance
• Polymorphism
• virtual methods / abstract classes
• RAII
• Examples of useful class designs ("design patterns" with less jargon)

Some of this can potentially go earlier (e.g. week 3) if this turns out to be overloaded and week 3 is too empty.

@mmcleod89