solve lectures colliding with pentecost break

This merge request is a suggestion to solve the issue #6 (closed) , i.e. May 21 is pentecost break and no lectures. I'd suggest to move the "User Experience Design" by one week as it fits nicely before the following ones after the pentecost break. "Good Scientific & Coding Practice" would then move to the end (July 9) and maybe be combined with the student talks if there are any.