Resolve name collsion of `first` and `second` by Control.Arrow and Data.Bifunctor

[Henning Thielemann]

On Wed, 9 May 2018, Wolfgang Jeltsch wrote:

> I think using Bifunctor.first and Bifunctor.second is as much an abuse 
> as using Arrow.first and Arrow.second. When using Arrow you specialize 
> the arrow type to (->), but when using Bifunctor you specialize the 
> bifunctor type to (,).

I actually use my own specialised mapFst and mapSnd functions from 
utility-ht. I also found that I sometimes need strict versions of these 
functions in order to prevent space leaks.