many1 and sepBy1 could return NonEmpty

It seems that these two functions in `Data.Attoparsec.Combinator` might have had `NonEmpty a` rather than `[a]` in their return types, since they are never supposed to yield an empty list.

```haskell
many1 :: Alternative f => f a -> f [a]
sepBy1 :: Alternative f => f a -> f s -> f [a]
```

Perhaps we might introduce additional combinators?

```haskell
manyNE :: Alternative f => f a -> f (NonEmpty a)
sepByNE :: Alternative f => f a -> f s -> f (NonEmpty a)
```

The code I'm writing at the moment applies `Data.List.last` to the result of `sepBy1`, and I believe being able to instead apply `Data.List.NonEmpty.last` to the result of `sepByNE` would bring me happiness.