v2.0-M8 exercise functions and revised lab blockmole ready for review

Tuples are not part of functions to make it smaller. The lab blockmole is now changed to include tuples. The structuring of the blockmole program into modules is made clear and a blockworm is introduced in the extra tasks. The complete tex of blockmole is revised to reflect its position in week 4 and the be shorter and easier to read.