Feature/offline tasks refactoring

TODOs:

• Get rid of dead code
• Move CS Training and Validation Code into continuum_suppression sub-package
• Break offline_tasks into several files for better maintainability
• Automate generation of selection samples
• Generate selection samples with some cuts not applied for sideband-studies
• Generate selection sample for Markus with no cut on q^2
• Implement sideband validation tasks
• Add FEI Correction Factor calculation to Analysis Tools and use it in Data Preparation Task
• Add Coulomb correction to other MC corrections in data preparation tasks
• Implement Cut Flow analysis
• Maybe apply cuts via pandas hdf5 store to avoid loading the whole data frame only to discard most of it