Examples on the use out of tasks are provided in:
`example/Tutorial3/digitization/TestDetectorDigiLoader.tpl:76-85`: sending a part.
`example/Tutorial3/reconstruction/FairTestDetectorMQRecoTask.tpl:177-182`: receiving a part.
- This commit also makes structure within processorTask more consistent with samplerTask.
- add macro MQLOG to FairMQLogger.