Add overloads for |> to value types that wrap functions

[JaapWijnen]

Would it make sense to add overloads for |> to types like Func and Endo (Maybe others, I've mainly used these).
This would clean up the call site since these types represent functions anyway. Then we don't have to call .call or .apply anymore

given:
let increment = Endo<Int> { value in value + 1 }
before:
let result = 5 |> increment.call
with overloads:
let result = 5 |> increment

This is not too bad ofcourse but it's really nice when chaining methods for example:
let result = 5 |> increment <> square <> increment
Would have to be wrapped in parentheses:
let result = 5 |> (increment <> square <> increment).call

Maybe this also applies to a few other types? I'd gladly add them if you think this would make sense :)

public func |> <A> (a: A, f: Endo<A>) -> A {
    return a |> f.call
}

public func |> <A, B> (a: A, f: Func<A, B>) -> B {
    return a |> f.call
}

Maybe it also applies to Parallel?

[stephencelis]

Thanks for bringing this up! This is relevant to #155, I believe.

I'm going to convert to a discussion, since we probably won't address directly in this repo anytime soon, but welcome discussion for downstream users/forks.