Formal verification of containers

[Henning Thielemann]

On Thu, 1 Feb 2018, David Feuer wrote:

> I don't think we should limit containers development like that. I do 
> imagine it would be valuable to have a separate package, perhaps called 
> verified-containers, that tries to stay a few weeks or months behind 
> containers.

I am happy to change all my dependencies from 'containers' to 
'containers-verified' (for easier association in a lexicographically 
ordered list).