`fmap` over a `dict` should `map` over the items, not `starmap`

[evhub]

Instead of

some_dict |> fmap$((k, v) -> (k, v + 1))

this change would require

some_dict |> fmap$(def ((k, v)) -> (k, v + 1))

which would keep the type signature of fmap more consistent.

Note that this would be a breaking change.