As a user, I want to save my progress through a course and among courses

Users want learnbash to remember their progress through a learner. Requirements:

1. a given installation of learnbash assumes there is only one "person" using it. i.e. there will be no login mechanism, or users to select, because that is boring and stupid.
2. Each course in the course list will be marked as completed, in progress, or not attempted. These will correspond to the user's actual progression through those courses.
3. The course statuses will be persistent across executions of learnbash.
4. Within a course, the same statuses (completed, in progress, not attempted) will be shown for each of that courses's lessons.
5. A lesson counts as complete iff all the exercises comprising it have been completed.
6. A course is complete iff all the lessons comprising it have been completed.
7. The user is presented with an option at the course level menu to erase all current progress.

Note, this issue should have a design plan of some sort to lay out exactly how this history will be stored on the filesystem.