Delete the existing dir before copying the new dir over it incase its
contents have changed.
Delete & Copy directories before tests are run.
On test runners the tests run in parallel so we can't write and clean
up at the start and end of each test. Unless each test copys the data to
a unique dir name. [This may be a better thing to do in the long run]
Use the whole width of the terminal assume width of 80 if none found
Show percentages in the final column. Show ASCII bars indicating usage
of the underlying directories in the space inbetween.
Display (height of terminal - 10) entries by default.
Reverse the output order so largest is at the bottom.
Break up tests. Change older tests to check real output of program.