Issue #32: python-engine: Retain module info for executed program

Solution taken from coverage.py,

  http://nedbatchelder.com/code/coverage/

also see

  http://stackoverflow.com/questions/23691509/unittest-py-doesnt-play-well-with-trace-py-why
python-engine: Ignore finally
robot-framework: Add regression-test for finally
Issue #32: robot-framework: Add regression test for unittest stuff