Show courses which are not being displayed in timetable

[npalladium]

Is your feature request related to a problem? Please describe.
When the extension is unable to add a course to the timetable, either because AIMS isn't showing the timetable or because we aren't able to parse the given timetable.

Describe the solution you'd like
Raise an alert when something like that. In the latter case, we could even log to our server.

Describe alternatives you've considered
You could also list those courses in the timetable.

[RachitKeertiDas]

Sounds like a pretty reasonable thing to do.