Fixed reloader_hierarchical

- fix: shapes were modified, now works properly.
Work on reloaders

- Added: Plots for fits to experimental histograms.
Tweaks and fixes

- Fix: default empty string values for job_name and session_id
- Add: Plot_histogram_bias_nontarget now performs a Vtest
- Add: Function to print a dictionary in a string, using a “key value, key value” format