3 tests corrected

Hi Ralf,
I tried to correct two of the tests which I mentioned in the previous pull request to fail sporadically:
  Output_with_fan_out
  Run_on_separate_thread
Both have a logic error as background, as I assume. Therefore I would ask you to check it seriously before pulling them. Of course I may have overseen something what you will see with your implementation background.
I tried to explain the problem well in the commit logs.

Sporadically there was coming up another error at tests: Check_if_data_is_not_retrieved_from_queue. I tried also to solve it. Seems the thread scheduling is different fast here between mono and the CLR.

The other two failed tests mention in my first pull request
  Causality_exception_messages_bypasses_other_pending_messages and
  High_prio_exception_message_terminates_runtime
still fail. I did not found time to analyze them. However, I tried it with NUnit under Windows XP and they also fail there, always. If you find some free minutes, please let both tests run again on your machine. I guess, there is something specific to the exception message priority handling.

Denis