First version of chapter 9-4 'Links en rechts hetzelfde'
Chapter 9-4 finished
Omslagpunt exercise added
Start with Pijlenketting exercise
Randomized variables for the Pijlenketting
Split up multiplication and addition
Fixes in the Pijlenketting exercise
Added colors to Pijlenketting exercise
Update the arrowchain itself in the Pijlenketting exercise
Added 'balans' problem to Pijlenketting exercise