Added unit testing for the Vector class

All unit testing must go in a different project. If you add the testing
classes in the DPMFinal project, you'll get errors when you try to run the
tests

The work-around I use is:
- create another project with the JUnit classes
- r-click the project
- choose Build path
- click Configure build path...
- choose Projects
- click Add
- add the DPMFinal project
- DONE

Now you can run the unit tests.
Note that the unit tests should probably not include anything related to
Lejos.