These files are used to build the test scripts. They 
actually exercise GraphViz::Data:Structure with the
tests that the scripts in t/ will run, optionally sending the
output to dotty so it can be checked visually, and rewriting the
test programs in the t/ directory. 

If you add new features or change old ones, it is
highly recommended that you run through all of these files
again to visually verify that the output looks the way 
you want. 

make_all.pl is provided to do a quick rebuild of all the tests 
witout running dotty. You *should* retry all the appropriate
tests (via perl build_test testname) to verify that the output
is visually OK when you make a change to the output routines.

REMEMBER: there's an 01basic.t test in t/ which isn't related
to these tests at all! It's just a basic functionality test.
Don't override it!