lml/ost — pull request #262 by kevinburleigh75 (2013-04-15 23:38:15+00:00)
Title: Exercise refresh fixes

This PR hardens the code against missing student answers due to exercise refreshes which remove answers. This will only work when the student's answer index doesn't match ANY existing answer index.

An "are you sure?" dialog has been added to the Learning Plan "Refresh Exercises" link to emphasize the need to carefully consider the consequences of changing exercises.