- Only for Tracker_LF and Tracker_MTS so far, Tracker_RK4 seems
      to contain different/additional logic. This should be clarified
      such that all trackers can use the same single particle dump
      code.
    - Initialization of trackOrbit-file done in initTrackOrbitFile
    - outf stream renamend to outfTrackOrbit_m, is now member variable
    - method singleParticleDump does the actual dump