refactoring of threading in tests

use a testthread instead of a worker now
each testthread receives a stackable in the constructor
the stackable will be run by the threads run method
refactor batcheventprocessor test to use the new testthread
batch event processor has an owm running method
this is needed because the isRunning() method by pthreads cannot be overridden
you can stop the batcheventprocessor by calling halt(), which would/could lead to an alert exception halting the batchevent processor during run()