Version 0.4.0

Added

• Show mean and median grade in plot.
• Add selection to show raw percentage in the plot.
• Visualize unposted student grades.
• Improve warning message for students with an unposted grade
  that would change their final grade.
• Allow filtering courses by date
  and only show last year's courses by default.
• Print version number and check for the latest version online.

Changed

• The grade drop threshold now applies to the unposted score.
  rather than the posted score.
• Make output notes and warnings stand out more.

Fixed

• Make end note easier to read.
• Provide a default value instead of crashing when a course is missing a name.