Improve general WTF-PAD code quality and maintainability
This is a master ticket for tasks that can be done after WTF-PAD gets merged, and maybe even after 0.4.0 gets released. They represent tasks that increase code quality and reduce tech debt.
Improve the probability distribution API. Instead of using nameless dist params, instead have the caller instantiate a struct with the right params for each distribution.
The above will also allow callers to specify a genpareto distribution with configurable