Include advanced data handling in workflow

Include all developments from #140 (closed), #141 (closed), #142 (closed), #143 (closed) into run_modules

• replace distributor by KerasIterator
• replace generator by DataCollection
• replace preparation by StationPrep + DataPrepration
• adjust data transformation
• adjust check stations
• all kwargs of StationPrep need to be implemented explicitly (like start, end)