Committing chapter 5 exercises
Revert "Committing chapter 5 exercises"

This reverts commit 52f518b31bc48daafc1886b9a042d517ff1a4b00.
Still on chapter 4 branch, oops
Revert "Revert "Committing chapter 5 exercises""

Restoring chapter 5 excercises
This reverts commit fe6cb03652cc0d744be327cbedf24b9990829cd6.
Merge pull request #17 from SandyThomson/ajd_chapter5

Ajd chapter5