1. `rating`, `rating_deviation`, and `rating_interval` all omit the
possibility of receiving a `nil` as the second argument.
2. Writing out `Result.t()` results in `dialyzer` looking for
`Elixir.Result.t()`, instead of calling the local
`Elixir.Glicko.Result.t()`.
Change the cases where a `do:` is followed by a `mix format` mandated
line break, or if the expression following the `do:` would span multiple
lines anyway.
The only exception to the rule above is the first change in the
changeset, as this was done for the function style of `initial_rating`
to be consistent with `initial_rating_deviation`.
