Converting the tests to use the unittest module

[snim2]

From the old Google Code repo:

Reported by project member sschwarzer@sschwarzer.net, Jul 23, 2010

Currently, the output of the tests is extensive but doesn't make clear whether the output is expected or if it indicates a failure. It might be better to use the unittest module from the Python standard library (or another testing framework) to clarify what the tests are supposed to do (or not) and to show the testrunner results in a way that can be grasped easily.