midilearn: Repeat exercises with errors
midilearn: Repeat exercises with errors

Summary:
If the user makes a mistake, ask them to repeat the given exercise until
they get it right.  This will help reinforce the correct answer, instead
of the incorrect.

Test Plan: Verify behavior with the examples.

Reviewers: d3zd3z

Reviewed By: d3zd3z

Maniphest Tasks: T2

Differential Revision: https://davidb.phacility.com/D26

d3zd3z/stenome,d3zd3z/stenome