Echosms

- 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

- Changed the API used to access the benchmark data
- Better error messages when using an unknown benchmark name. Resolves 27

- Fixes a bug in the previous release in the KRM code