Merge in "08-mappings"

Merge branch "08-mappings" into "develop"

Summary of the merged in commits:
 * 7fee5f55: Add review and exercises for notebook 08
 * b7ad1714: Add initial version of notebook 08
 * c69687f4: Add exercise on packing/unpacking with functions
 * ca8fefdc: Streamline previous content
 * fe138176: Add note for lecture in spring term 2020
 * 675dbc43: Adjust content overview in README.md