refactor: deprecate connection value

[rgrinberg]

In it's current form it's completely useless. It should be implemented by the individual
backends where it will gain meaning and functionality.

[mseri]

Once we remove Connection.t, will the solution just be to rewirte the module separately in cohttp-lwt and cohttp-mirage?

[rgrinberg]

I don't the details for mirage, but for Unix, I imagine it would look like:

module Context : sig
  type t
  val sockaddr : t -> Unix.sockaddr
end

I don't quite like the name Connection because it might not be all that meaningful behind a proxy or fcgi.

[mseri]

Ok, so the idea is to deprecate it and replace it with something else. Maybe we should also introduce the replacement here, to also see what it looks like, and redefine module Connection = Context (this should allow old code to compile, right?)

[rgrinberg]

Sure, I can work on introducing the replacement here. Although i'll note that no functionality is lost by getting rid of this module. In its current form, it cannot be used to do anything other than break the statelessness of the HTTP protocol.

[mseri]

Ok, fair enough. Let's merge in the meantime then