- New Problem model: `models.cost_based.TimetableScenario`
- minimizes costs, enabling new constraints
- more flexible under conflicting constraints
- more direct problem data mapping, for input and output
- added penalty sources as output
- methods for executing itself
- Breaking changes:
- `tomato_cooker.models.tomatic.MODEL_DEFINITION_PATH`
can now be found as `tomato_cooker.models.tomatic.TomaticProblem.model_path`