Bump version to 0.24.0
Add documentation for compute_eval_from_predictions.
Make skll.metrics.use_score_func publicly available.

- Also switch compute_eval_from_predictions to use use_score_func
- Add --version option and other niceties to compute_eval_from_predictions
fixed typo in LICENSE: ETSs -> ETS
Fix typo in LICENSE.txt
Merge branch 'release/0.24.0' of github.com:EducationalTestingService/skll into release/0.24.0
Merge branch 'release/0.24.0' into develop