- Use StratifiedKFold instead of KFold to also stratify each single fold
- Fix bug that would always down-sample when running uncompressed FNN
- Fix all log outputs and string formattings
- Add forgotten y_one_hot in a conditional branch
- Make unknown loss function fail explicitly
- Improve collecting the performance metrics for all targets and folds

God, I hope I didn't break something. Looks good so far.