Quote output correctly
Remove copied data files on distclean
Use provided filenames instead of hardcoded list
Make sure that datafiles are copied when tests are made

That way, if someone runs `make test`, the datafiles will be there if
the testing programs are there, and the tests won't fail (because of
that).
Change directory with test driver for older CMakes

The WORKING_DIRECTORY property wasn't added until 2.8.4; for versions
earlier than that we provide a work-around. On newer versions we set the
property since some other components may use it.
Fix dependencies between test programs and datafiles

Apparently, DEPENDS can only be used between file-level dependencies
and not target-level dependencies. add_dependencies must be used for
that.
Merge pull request #155 from rolk/153_datafiles

Make `make test` work on release builds