Isolated Execution of Exercises

[bbuck]

This is a pretty standard concept, I know of a project called Exercism that has this same pattern for teaching for a variety of other languages. One thing I think is important in this is being able to execute exercises in isolation from each other. For example upon pulling and running nimble run on the project the first immediate failure was exercise 2, despite having not even opened exercise 1 and solved it. It would have been great to execute the exercises in order.