Fix: Automatically find all sub packages in setup.py

or else add the validation_studies to the sub packages manually

this avoids

Traceback (most recent call last):
  File "./offline.py", line 3, in <module>
    from rdstar.offline_analysis.offline_tasks import OfflineAnalysisMaster
  File "/home/klieret/.local/lib/python3.6/site-packages/rdstar/offline_analysis/offline_tasks.py", line 36, in <module>
    from rdstar.offline_analysis.tracking_corrections import TrackingEffCorrector
  File "/home/klieret/System/installations/basf2/externals/v01-07-01/Linux_x86_64/opt/root/lib/ROOT.py", line 461, in _importhook
    return _orig_ihook( name, *args, **kwds )
  File "/home/klieret/.local/lib/python3.6/site-packages/rdstar/offline_analysis/tracking_corrections.py", line 9, in <module>
    from analysistools.tracking_correction.tracking_correction import TrackingCorrection
  File "/home/klieret/System/installations/basf2/externals/v01-07-01/Linux_x86_64/opt/root/lib/ROOT.py", line 461, in _importhook
    return _orig_ihook( name, *args, **kwds )
ModuleNotFoundError: No module named 'analysistools.tracking_correction'