Cardano Updates

NE.singleton doesn't exist until a later version of base.

This commit adds an alternative attempt at generics. It has both
advantages and disadvantages.

The principal advantage is that it really allows generics to work with
HuddleM - see the example in example/Monad.hs for a demonstration. The
previous way of writing this was quite horrible.

There are two main disadvantages:

- Now, rather than treating a generic function as a regular Haskell
function, we have to treat it specially and call it with the special
syntax (<--).
- Only one generic parameter is supported. We can potentially fix this,
but it's always going to play unkindly with the (<--) syntax. That
having been said, we had only implemented up to two parameters before.

For these reasons, these new-style generics are currently implemented
alongside the existing ones for consideration.

Add optics for modifying name and comment