scripts folder reorganization:
- renamed wf_febs_1.py into solver_comparison.py
- merged wf_febs_3.py and wf_febs_4.py into data_generation.py
- merged wf_febs_5.py and wf_febs_6.py into parameter_estimation.py
- completed data_generation and parameter_estimation scripts;
- added missing accessors to workflow.py;
- fitted model simulation after parameter estimation now done on the statistics side using a deep copy of the considered biopredyn.simulation.UniformTimeCourse object;
- libsbmlsim result processing now takes into account the difference between output_start_time and initial_time in SED-ML experiment description.