Epsilon without Num

There doesn't seem to be anything in `Epsilon` that would require instances to also be instances of `Num`. I have some numeric `newtype`s that I'm making `Additive` but not full instances of `Num` that I'd like to still be `Epsilon`. Could the `Num` constraint be removed?

For instance, for dimensioned quantities:

```haskell
newtype Angle = Radians Double
-- with appropriate instances, but not Num

birotate :: Angle -> Angle -> Point -> Point
birotate a1 a2
| nearZero da = id
| otherwise = mkRotation da
where
da = a1 + a2
```