v2.2.1

Transition Functions and the History Stamp

This patch addresses the accessibility of the HistoryStamp. Previously, the stamp only recorded all overdoses, state, and intervention admissions. This made accessing the fatal overdoses and the background mortality metrics difficult to obtain. Thus, we added some new trackers to the HistoryStamp and broke out the stamper behavior. Instead of having unique stamper functions to record the history stamp we instead applied the HistoryStamp as a parameter to each transition function so it can be adjusted there.

Additionally, all transition functions saw their state parameter turned into a const variable to prevent accidental mutation. Instead, we now expect the pattern to be a const state, const transition, and mutable history stamp passed in to the transition and a resultant state vector returned. This required some changes to the overdose transition model.

Finally, we also addressed some bugs in the model around calculating the background mortality. Previously we were returning the people that died rather than the people that survived.