Rotate confusion matrix

Rotate the confusion matrix, such that rows are normalized to unity. The old behavior could be available via a flag.

assigned to @fsauerbu

created merge request !27 (merged) to address this issue

mentioned in merge request !27 (merged)

The matrix should not be actually rotated. The labels should all stay the same. However, there should be an option to normalize_rows.

closed via merge request !27 (merged)