Make Prelude's map = fmap (Nikita Volkov)

[Henning Thielemann]

On Fri, 21 Jun 2013, Gabriel Gonzalez wrote:

> +1
> 
> I'm in favor of generalizing `map`.  At first I was wary of less monomorphic types, but now I've found that
> it's not that hard to just lie and pretend the type is more specialized when teaching.  Plus, `map` is a
> much nicer name than `fmap`.

We could also have Functor.map, if people would get familiar with 
qualified imports.