Put the test suite test case before the individual test cases that are done within a test suite.

GTestSuite::run starts with creating a test case that collects the total time spent in a test and that also collects any failures of the individual test cases. Before, this test case was appended AFTER running the individual test cases, which led to an XML file out of order. Now the general test case is appended BEFORE running the test cases.
Track results of Python unit tests (#1119)

The results of the Python unit test were not correctly tracked due to some subtle problems related to the way how C++ code is called through the Python interface. A kluge has been found and added to GTestSuite.i to retrieve the Python test results and to propagate them to the C++ test suite, so now Python test results are also written into the XML file, and the Python tests signal failure in case that something goes wrong.