Add event scale metrics to metrics

[jarq6c]

Adds hydrotools.metrics.events module with three basic methods.

Additions

• flashiness
• peak
• runoff_ratio

Removals

Changes

Testing

Notes

Todos

Checklist

• PR has an informative and human-readable title
• PR is well outlined and documented. See #12 for an example
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (see CONTRIBUTING.md)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output) using numpy docstring formatting
• Placeholder code is flagged / future todos are captured in comments
• Reviewers requested with the Reviewers tool ➡️

[christophertubbs]

Fantastic code and documentation. Extend some of that to your unit tests for perfection.

One habit that may be worth trying out is assigning a computed value prior to returning it. Makes it easier to debug in certain circumstances, especially when there are many moving parts to the calculation. That's not worth changing, just mulling about.

[jarq6c]

Thanks for the review @christophertubbs ! I've implemented all the improvements you recommended.