Currently, the function do_OneSite is a tapeworm of code. This is hard to read, develop, and maintain.

Ideally, every aggregation option is its own unit of code encapsulated in a function. This would allow easier unit testing and makes these aggregation functions available to users of the package, e.g., the STEPWAT2 wrapper.

Ideally, we would also allow the user to choose what type of aggregations (e.g., mean, median, sd, quantiles, ...) to calculate and allow the option to provide yearly output as well.