modify all existing exercises (and set as standard in the future course uploads)
to have a max score of 100 instead of ncorrect. normalize existing exercise
scores as expected and alter performance reports to make sense.
this may noy be as bad as i thought
turns out this can be done with a fairly simple database tweak, at least to
convert a functioning system.
did the bugzilla DB revert? I thought I'd marked all these live. Anyway these
fixes should be live now.