Description

This PR adds animal consumption of litter to the Virtual Ecosystem. To resolve the timing issue that arises in coupling the two models, animals consume litter first and then the remainder decays (this may have to be worked on in future).

Fixes #545

Type of change

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist

• Make sure you've run the pre-commit checks: $ pre-commit run -a
• All tests pass: $ poetry run pytest

Further checks

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works
• Relevant documentation reviewed and updated