Exercise Mode Editing Capabilities

[russell-rozenbaum]

Added Features

Adds ability to edit several exercise mode features:

• Title
• Module name
• Prompt
• Number of Mutation Tests
• Required Tests
• Point Distributions

Also implements the following:

1. Exercise's storage keying system now uses UUIDs rather than (string, int) pairs. *Note: this change removes the previous version field, represented by the int in the pair of the old keying system
2. persistent_state type in exercise mode has been made into a record. Along with the zipper position and editors it stores the title and list of mutants. This allows for mutants to be persisted and unpersisted upon saving and loading to and from local storage.

Caveats

• Exercise modules must have a hardcoded UUID in their spec file to save and load properly. A potential solution can be to initialize a UUID and update the spec when first loading. This would require mutating the spec file however. This shouldn't prove to be much of an issue when creating new exercises.
• Future implementations requiring saving and loading mutable features to and from storage will need to be added in the record and persisted/unpersisted properly in their respective functions. This isn't as much of a pitfall, as it is a note to help future implementations.