Make a timeline

[ehmatthes]

• Make a CriticalEvent class.
  • Represents either a critical period, with or without a slide, or a slide without a critical period.
  • This is what's sent to plotting functions.
• Generate a timeline of all critical events.
  • Helps answer questions such as, "Are slides becoming more frequent?"
  • This repository should be maintained for next ~5-10 years for a full picture of ongoing slide risk through ongoing climate change.
  • See: https://matplotlib.org/3.2.1/gallery/lines_bars_and_markers/timeline.html
  • Write a test for the timeline that's generated.