Make ant run junit4.

I added the ant-junit4 library from my ant distribution.  This fixed a bug where the ant junit task by default tries to run junit3 and failed on almost all tests
Fixed user termination request.

There was still one point in the DPLLEngine where we did not check for user termination requests but for timeouts.
Additionally the test case for this feature was broken and has been changed since the termination request is not directly related to decisions