Make knitted a case class.
Factor out Yarns in test.
Step no longer extends function because that breaks the toString.
Add AllNeedesToX values.
Add optimizer for plans.
Fix AddCarriage.
Add Optimizer for settings.
Fix GuideStep.apply.
Get rid of optimization checking (can fail because of anon functions even though it is identical.
No longer need to check for the current carriage settings. The optimizers will take care of that.