Slight updates (multiple choice, and obsolete messages)

• Someone pointed out what information you could get out of the multiple choice thing, so I tweaked it. And I had second thoughts about one of the questions, so ... 
• A few of this week's messages point to dead links because revisions are published under different filenames. I will remove some obsolete messages.

Thanks for the [very sparse!] feedback. Again, you find Olav's e-mail address atop the Lectures section in Canvas.