Minor fixes to mandatory assignment files

There was a few errors in the original Makefile, which made it difficult to use on IFI-machines. I have therefore made some updates to the files, so if you are having problems, please download the latest Makefile linked to from the oblig text, and run "make setup" to get the newest versions of the programs. However, you do not need to do this if everything works fine :)

- Leif Harald