[script.*] Change prediction to write dataset predictions on a subfolder named after the dataset name in the current run

[script.analyze] Issue warning if keys do not match on for second-annotator evaluations (should not happen, normally)

[script.evaluate] Fix second-annotator comparisons with a key-resemblance check; Add assertions in engine.evaluator to ensure proper comparisons

Cleanup model implementation

See merge request bob/bob.ip.binseg!13