[FEATURE] Pass single object instead of 3 args into epics

[Sawtaytoes]

Do you want to request a feature or report a bug?
Feature

What is the current behavior?

const someEpic = (
  action$,
  state$,
  dependencies,
) => (
  action$
  .pipe(
    // etc
  )
)

What is the expected behavior?

const someEpic = ({
  action$,
  state$,
  ...dependencies,
}) => (
  action$
  .pipe(
    // etc
  )
)

Which versions of redux-observable, and which browser and OS are affected by this issue? Did this work in previous versions of redux-observable?
All 0.x.x and 1.x.x versions.

I think the argument list for an epic needs to change. Because of the way the arguments are setup, I think it can be confusing to new users. For instance, I never thought to pipe off state$ directly until after 9 months of near-daily use. Personally, I also see 3 arguments as too many. At the point you have 3 arguments, it should probably be sending those arguments as named-props instead.

I'd like to see a single object instead. This would make it a lot easier to reach your dependencies. For instance, you might not use action$ or state$ but need some dependency. In the majority case though, you're going to either use action$ or state$ and possibly a dependency. Wouldn't it be easier to select them out of a single object rather than naming all 3 arguments?

I'm sure this can be deprecated so long as you don't use uglify:

const isUsingOldApi = (
  epicCreator,
) => (
  epicCreator.length > 1
  || (
    epicCreator
    .toString()
    .split(' ')
    .join('')
    .includes('(action$')
  )
)

const combineEpics = (
  (
    action$,
    state$,
    dependencies,
  ) => (
    (...epicCreators) => (
      epicCreators
      .map(epicCreator => (
        isUsingOldApi(
          epicCreator,
        )
        ? (
          deprecationMessage(
            "Using old API version. Get with the times.",
            epicCreator(
              action$,
              state$,
              dependencies,
            ),
          )
        )
        : (
          epicCreator({
            ...dependencies,
            action$,
            state$,
          })
        )
      ))
    )
  )
}

Reading this, I just realized I could do the same thing and not bother making it official, but then I'd have epics that don't match anything else out there. Doesn't seem like a best-practice situation to be the odd man out.