[Graeme] Completed chapter 4.
[Graeme] Chapter 5 examples completed
[Graeme] Some chapter 5 exercises
[Graeme] Completed chapter 5 exercises
[G] Deleted class files
[Graeme] Chapter 06
[G] Chapter 7 complete
[G] Tidied up some package structures
[Graeme] Chapter 8 lectures
[Graeme] Completed chapter 8
[Graeme] Chapter 9 completed