Echosms

More tweaks for the WGFAST 2025 presentation

- Add more tests
- Documentation edits
- Add plot() method to the KRMorganism class

This release was prepared for the 2025 WGFAST meeting and echoSMs workshop, 5-11 April.

- API change to ReferenceModel class. An empty dict is returned instead of an empty list when no ReferenceModel data is available.
- Improve documentation in places
- Add pytest tests for TS output from all models

- bug fix for units in BenchmarkData
- Update tutorial notebook for new BenchmarkData API

None

Multiprocessing:
- Add support for a progress bar when multiprocessing
- Improve multiprocessing documentation
- Make multiprocessing library a formal dependency

Bug fixes
- Significantly increase the speed of parameter checking when running large numbers of models

Benchmark data
- Update the docs to match the new way of accessing the benchmark data